Convert CONFIG_BOARD_COMMON to Kconfig

This converts the following to Kconfig:
   CONFIG_BOARD_COMMON

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-exynos/Kconfig
index 6087d93..f73dbbb 100644
--- a/arch/arm/mach-exynos/Kconfig
+++ b/arch/arm/mach-exynos/Kconfig
@@ -1,5 +1,9 @@
 if ARCH_EXYNOS
 
+config BOARD_COMMON
+	def_bool y
+	depends on !TARGET_SMDKV310 && !TARGET_ARNDALE
+
 choice
 	prompt "EXYNOS architecture type select"
 	optional