ARM: EXYNOS: Make ARCH_EXYNOS select USE_OF

Since EXYNOS is now DT-only, it always requires USE_OF option to be
selected. This patch moves USE_OF selection from entries of DT board
files to ARCH_EXYNOS.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 49d993c..fc20cfc 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -796,6 +796,7 @@
 	select HAVE_S3C_RTC if RTC_CLASS
 	select NEED_MACH_GPIO_H
 	select NEED_MACH_MEMORY_H
+	select USE_OF
 	help
 	  Support for SAMSUNG's EXYNOS SoCs (EXYNOS4/5)