arm: rmobile: kconfig: Remove '+S:' prefix from defconfig files

'+S' is unnecessary because boards of rmobile do not use SPL.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
CC: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/configs/alt_defconfig b/configs/alt_defconfig
index 0655e60..d722306 100644
--- a/configs/alt_defconfig
+++ b/configs/alt_defconfig
@@ -1,3 +1,3 @@
 CONFIG_ARM=y
-+S:CONFIG_RMOBILE=y
+CONFIG_RMOBILE=y
 CONFIG_TARGET_ALT=y