versatile: kconfig: move common settings

Move Versatile-specific settings to versatile/Kconfig.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/configs/versatilepb_defconfig b/configs/versatilepb_defconfig
index fadaf93..2c59e5c 100644
--- a/configs/versatilepb_defconfig
+++ b/configs/versatilepb_defconfig
@@ -1,3 +1,3 @@
 CONFIG_SYS_EXTRA_OPTIONS="ARCH_VERSATILE_PB"
 CONFIG_ARM=y
-CONFIG_TARGET_VERSATILEPB=y
+CONFIG_ARCH_VERSATILE=y