kconfig: remove meaningless prefixes in defconfig files

Since commit e02ee2548afe (kconfig: switch to single .config
configuration), the prefixes in defconfig files such as "+S:",
"+ST:", etc., are meaningless.

This commit was generated by the following command:

  find configs -name '*_defconfig' | xargs sed -i 's/^+*S*T*://'

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/configs/Cubietruck_defconfig b/configs/Cubietruck_defconfig
index b64f84f..5c23bc7 100644
--- a/configs/Cubietruck_defconfig
+++ b/configs/Cubietruck_defconfig
@@ -2,9 +2,9 @@
 CONFIG_SYS_EXTRA_OPTIONS="AXP209_POWER,SUNXI_GMAC,RGMII,AHCI,SATAPWR=SUNXI_GPH(12),USB_EHCI"
 CONFIG_FDTFILE="sun7i-a20-cubietruck.dtb"
 CONFIG_VIDEO_VGA=y
-+S:CONFIG_ARM=y
-+S:CONFIG_ARCH_SUNXI=y
-+S:CONFIG_MACH_SUN7I=y
-+S:CONFIG_DRAM_CLK=432
-+S:CONFIG_DRAM_ZQ=127
-+S:CONFIG_DRAM_EMR1=4
+CONFIG_ARM=y
+CONFIG_ARCH_SUNXI=y
+CONFIG_MACH_SUN7I=y
+CONFIG_DRAM_CLK=432
+CONFIG_DRAM_ZQ=127
+CONFIG_DRAM_EMR1=4