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/Linksprite_pcDuino3_defconfig b/configs/Linksprite_pcDuino3_defconfig
index 45d88f3..e642069 100644
--- a/configs/Linksprite_pcDuino3_defconfig
+++ b/configs/Linksprite_pcDuino3_defconfig
@@ -1,9 +1,9 @@
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="AXP209_POWER,SUNXI_GMAC,AHCI,SATAPWR=SUNXI_GPH(2),USB_EHCI"
 CONFIG_FDTFILE="sun7i-a20-pcduino3.dtb"
-+S:CONFIG_ARM=y
-+S:CONFIG_ARCH_SUNXI=y
-+S:CONFIG_MACH_SUN7I=y
-+S:CONFIG_DRAM_CLK=480
-+S:CONFIG_DRAM_ZQ=122
-+S:CONFIG_DRAM_EMR1=4
+CONFIG_ARM=y
+CONFIG_ARCH_SUNXI=y
+CONFIG_MACH_SUN7I=y
+CONFIG_DRAM_CLK=480
+CONFIG_DRAM_ZQ=122
+CONFIG_DRAM_EMR1=4