ARM: s3c64xx: use "depends on" instead of "if" after prompt

This platform recently moved to multi-platform, so missed the global
fixup by commit e3246542 ("ARM: use "depends on" for SoC configs
instead of "if" after prompt").  Fix it now.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>

arch/arm/mach-s3c64xx/Kconfig

@@ -3,7 +3,8 @@
 #
 # Licensed under GPLv2
 menuconfig ARCH_S3C64XX
-	bool "Samsung S3C64XX" if ARCH_MULTI_V6
+	bool "Samsung S3C64XX"
+	depends on ARCH_MULTI_V6
 	select ARCH_REQUIRE_GPIOLIB
 	select ARM_AMBA
 	select ARM_VIC