arm: add support for SoC s5p4418 (cpu) / nanopi2 board

Changes in relation to FriendlyARM's U-Boot nanopi2-v2016.01:
- SPL not supported yet --> no spl-dir in arch/arm/cpu/armv7/s5p4418/.
  Appropriate line in Makefile removed.
- cpu.c: '#include <cpu_func.h>' added.
- arch/arm/cpu/armv7/s5p4418/u-boot.lds removed, is not required
  anylonger.
- "obj-$(CONFIG_ARCH_NEXELL) += s5p-common/" added to
  arch/arm/cpu/armv7/Makefile since s5p-common/pwm.c is used instead
  of drivers/pwm/pwm-nexell.c.
- s5p4418.dtsi: '#include "../../../include/generated/autoconf.h"'
  removed, is not necessary, error at out-of-tree building.
  '#ifdef CONFIG_CPU_NXP4330'-blocks (2x) removed. Some minor changes
  regarding mmc. 'u-boot,dm-pre-reloc' added to dp0 because of added
  DM_VIDEO support.
- board/s5p4418/ renamed to board/friendlyarm/
- All s5p4418-boards except nanopi2 removed because there is no
  possibility to test the other boards.
- Kconfig: Changes to have a structure like mach-bcm283x (RaspberryPi),
  e.g. "config ..." entries moved from/to other Kconfig.
- "CONFIG_" removed from several s5p4418/nanopi2 specific defines
  because the appropriate values do not need to be configurable.
- nanopi2/board.c: All getenv(), getenv_ulong(), setenv() and saveenv()
  renamed to env_get(), env_get_ulong(), env_set() and env_save(),
  respectively. MACH_TYPE_S5P4418 is not defined anymore, therefore
  appropriate code removed (not necessary for DT-kernels).
- nanopi2/onewire.c: All crc8() renamed to crc8_ow() because crc8() is
  already defined in lib/crc8.c (with different parameters).
- dts: "nexell,s5pxx18-i2c" used instead of "i2c-gpio", i2c0 and
  i2c1 added. gmac-, ehci- and dwc2otg-entries removed because the
  appropriate functionality is not supported yet. New mmc-property
  "mmcboost" added.
  s5p4418-pinctrl.dtsi: gmac-entries removed, mmc- and i2c-entries
  added.
- '#ifdef CONFIG...' changed to 'if (IS_ENABLED(CONFIG...))' where
  possible (and similar).

Signed-off-by: Stefan Bosch <stefan_b@posteo.net>
diff --git a/arch/arm/dts/s5p4418-nanopi2.dts b/arch/arm/dts/s5p4418-nanopi2.dts
new file mode 100644
index 0000000..4deaf10
--- /dev/null
+++ b/arch/arm/dts/s5p4418-nanopi2.dts
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2020 Stefan Bosch <stefan_b@posteo.net>
+ *
+ * (C) Copyright 2017 FriendlyElec Computer Tech. Co., Ltd.
+ * (http://www.friendlyarm.com)
+ *
+ * (C) Copyright 2016 Nexell
+ * Youngbok, Park <park@nexell.co.kr>
+ */
+
+/dts-v1/;
+#include "s5p4418.dtsi"
+
+/ {
+	model = "FriendlyElec boards based on Nexell s5p4418";
+	cpu-model = "S5p4418";
+
+	compatible = "friendlyelec,nanopi2",
+		     "nexell,s5p4418";
+
+	aliases {
+		mmc0 = "/mmc@c0069000";
+		mmc1 = "/mmc@c0062000";
+		i2c0 = "/i2c@c00a4000";
+		i2c1 = "/i2c@c00a5000";
+		i2c2 = "/i2c@c00a6000";
+	};
+
+	mmc0:mmc@c0062000 {
+		frequency = <50000000>;
+		drive_dly = <0x0>;
+		drive_shift = <0x03>;
+		sample_dly = <0x00>;
+		sample_shift = <0x02>;
+		mmcboost = <0>;
+		status = "okay";
+	};
+
+	mmc2:mmc@c0069000 {
+		frequency = <50000000>;
+		drive_dly = <0x0>;
+		drive_shift = <0x03>;
+		sample_dly = <0x00>;
+		sample_shift = <0x02>;
+		mmcboost = <0>;
+		status = "okay";
+	};
+
+	/* NanoPi2: Header "CON2", NanoPC-T2: EEPROM (MAC-Addr.) and Audio */
+	i2c0:i2c@c00a4000 {
+		status ="okay";
+	};
+
+	/* NanoPi2: Header "CON2" and HDMI, NanoPC-T2: HDMI */
+	i2c1:i2c@c00a5000 {
+		status ="okay";
+	};
+
+	/* NanoPi2: LCD interface, NanoPC-T2: LCD, LVDS and MIPI interfaces */
+	i2c2:i2c@c00a6000 {
+		status ="okay";
+	};
+
+	dp0:dp@c0102800 {
+		status = "okay";
+		module = <0>;
+		lcd-type = "lvds";
+
+		dp-device {
+			format = <0>;	/* 0:VESA, 1:JEIDA */
+		};
+
+		dp-sync {
+			h_active_len = <1024>;
+			h_front_porch = <84>;
+			h_back_porch = <84>;
+			h_sync_width = <88>;
+			h_sync_invert = <0>;
+			v_active_len = <600>;
+			v_front_porch = <10>;
+			v_back_porch = <10>;
+			v_sync_width = <20>;
+			v_sync_invert = <0>;
+		};
+
+		dp-ctrl {
+			clk_src_lv0 = <3>;
+			clk_div_lv0 = <16>;
+			clk_src_lv1 = <7>;
+			clk_div_lv1 = <1>;
+			out_format = <2>;
+		};
+
+		dp-planes {
+			layer_top {
+				screen_width = <1024>;
+				screen_height = <600>;
+				back_color = <0x0>;
+			};
+
+			layer_1 {	/* RGB 1 */
+				width = <1024>;
+				height = <600>;
+				format = <0x06530000>;
+				pixel_byte = <4>;
+			};
+		};
+	};
+};