ARM: Rmobile: Rename CONFIG_RMOBILE to CONFIG_ARCH_RMOBILE

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/configs/silk_defconfig b/configs/silk_defconfig
index f5d7afd..02ba88a 100644
--- a/configs/silk_defconfig
+++ b/configs/silk_defconfig
@@ -1,5 +1,5 @@
 CONFIG_ARM=y
-CONFIG_RMOBILE=y
+CONFIG_ARCH_RMOBILE=y
 CONFIG_TARGET_SILK=y
 CONFIG_BOOTDELAY=3
 # CONFIG_CMD_BDI is not set