kconfig: remove meaningless prefixes in defconfig files

Since commit e02ee2548a (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>

configs/A13-OLinuXino_defconfig

@@ -10,9 +10,9 @@ CONFIG_VIDEO_VGA_VIA_LCD_FORCE_SYNC_ACTIVE_HIGH=y
 CONFIG_VIDEO_LCD_MODE="x:800,y:480,depth:18,pclk_khz:33000,le:16,ri:209,up:22,lo:22,hs:30,vs:1,sync:3,vmode:0"
 CONFIG_VIDEO_LCD_POWER="AXP0-0"
 CONFIG_VIDEO_LCD_BL_PWM="PB2"
-+S:CONFIG_ARM=y
-+S:CONFIG_ARCH_SUNXI=y
-+S:CONFIG_MACH_SUN5I=y
-+S:CONFIG_DRAM_CLK=408
-+S:CONFIG_DRAM_ZQ=123
-+S:CONFIG_DRAM_EMR1=0
+CONFIG_ARM=y
+CONFIG_ARCH_SUNXI=y
+CONFIG_MACH_SUN5I=y
+CONFIG_DRAM_CLK=408
+CONFIG_DRAM_ZQ=123
+CONFIG_DRAM_EMR1=0