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/am335x_evm_nor_defconfig b/configs/am335x_evm_nor_defconfig
index ed72af6..4826057 100644
--- a/configs/am335x_evm_nor_defconfig
+++ b/configs/am335x_evm_nor_defconfig
@@ -3,6 +3,6 @@
 CONFIG_SPL_STACK_R_ADDR=0x82000000
 CONFIG_SYS_EXTRA_OPTIONS="NAND"
 CONFIG_CONS_INDEX=1
-+S:CONFIG_ARM=y
-+S:CONFIG_TARGET_AM335X_EVM=y
+CONFIG_ARM=y
+CONFIG_TARGET_AM335X_EVM=y
 CONFIG_NOR=y