arm64: mvebu: Add support for the Marvell Armada 3700 SoC

The Armada 3700 integrates the following interfaces (not complete list):
- Dual Cortex-A53 ARMv8
- USB 3.0
- SATA 3.0
- PCIe 2.0
- 2 x Gigabit Ethernet 1Gbps / 2.5Gbps
- ...

This patch adds basic support for this ARMv8 based SoC into U-Boot.
Future patches will integrate other device drivers and board support
for the Marvell DB-88F3720 development board.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Kostya Porotchkin <kostap@marvell.com>
Cc: Wilson Ding <dingwei@marvell.com>
Cc: Victor Gu <xigu@marvell.com>
Cc: Hua Jing <jinghua@marvell.com>
Cc: Terry Zhou <bjzhou@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
diff --git a/arch/arm/mach-mvebu/Kconfig b/arch/arm/mach-mvebu/Kconfig
index 0fd71a7..f169fc5 100644
--- a/arch/arm/mach-mvebu/Kconfig
+++ b/arch/arm/mach-mvebu/Kconfig
@@ -1,14 +1,37 @@
 if ARCH_MVEBU
 
+config ARMADA_32BIT
+	bool
+	select CPU_V7
+	select SUPPORT_SPL
+	select SPL_DM
+	select SPL_DM_SEQ_ALIAS
+	select SPL_OF_CONTROL
+	select SPL_SIMPLE_BUS
+
+config ARMADA_64BIT
+	bool
+	select ARM64
+
+# ARMv7 SoCs...
 config ARMADA_375
 	bool
+	select ARMADA_32BIT
 
 config ARMADA_38X
 	bool
+	select ARMADA_32BIT
 
 config ARMADA_XP
 	bool
+	select ARMADA_32BIT
+
+# ARMv8 SoCs...
+config ARMADA_3700
+	bool
+	select ARM64
 
+# Armada XP/38x SoC types...
 config MV78230
 	bool
 	select ARMADA_XP
@@ -26,7 +49,7 @@
 	select ARMADA_38X
 
 choice
-	prompt "Marvell MVEBU (Armada XP/375/38x) board select"
+	prompt "Marvell MVEBU (Armada XP/375/38x/3700) board select"
 	optional
 
 config TARGET_CLEARFOG