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/MSI_Primo81_defconfig b/configs/MSI_Primo81_defconfig
index 6657ad6..b6aa876 100644
--- a/configs/MSI_Primo81_defconfig
+++ b/configs/MSI_Primo81_defconfig
@@ -21,10 +21,10 @@
 CONFIG_VIDEO_LCD_BL_EN="PA25"
 CONFIG_VIDEO_LCD_BL_PWM="PH13"
 CONFIG_USB_KEYBOARD=n
-+S:CONFIG_ARM=y
-+S:CONFIG_ARCH_SUNXI=y
-+S:CONFIG_MACH_SUN6I=y
-+S:CONFIG_DRAM_CLK=360
-+S:CONFIG_DRAM_ZQ=122
+CONFIG_ARM=y
+CONFIG_ARCH_SUNXI=y
+CONFIG_MACH_SUN6I=y
+CONFIG_DRAM_CLK=360
+CONFIG_DRAM_ZQ=122
 # Wifi power
-+S:CONFIG_AXP221_DLDO1_VOLT=3300
+CONFIG_AXP221_DLDO1_VOLT=3300