arm: add mach-nexell (header files)

Changes in relation to FriendlyARM's U-Boot nanopi2-v2016.01:
- DM_VIDEO support (display_dev.h).
- boot0.h added, handles NSIH --> tools/nexell obsolete.
- gpio.h: Include-path to errno.h changed.

Signed-off-by: Stefan Bosch <stefan_b@posteo.net>
diff --git a/arch/arm/mach-nexell/include/mach/sec_reg.h b/arch/arm/mach-nexell/include/mach/sec_reg.h
new file mode 100644
index 0000000..e3ae5ac
--- /dev/null
+++ b/arch/arm/mach-nexell/include/mach/sec_reg.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0+
+ *
+ * (C) Copyright 2016 Nexell
+ * Youngbok, Park <park@nexell.co.kr>
+ */
+
+#define NEXELL_L2C_SEC_ID	0
+#define NEXELL_MALI_SEC_ID	2
+#define NEXELL_MIPI_SEC_ID	4
+#define NEXELL_TOFF_SEC_ID	6
+
+int write_sec_reg_by_id(void __iomem *reg, int val, int id);
+int read_sec_reg_by_id(void __iomem *reg, int id);
+int read_sec_reg(void __iomem *reg);
+int write_sec_reg(void __iomem *reg, int val);