sf: Move SPI flash drivers to defconfig

There are already Kconfig options for SPI flash drivers, but we
have not moved them from config.h to defconfig files. This commit
does this in a batch.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/configs/T1042RDB_PI_NAND_defconfig b/configs/T1042RDB_PI_NAND_defconfig
index f07e86e..fb229df 100644
--- a/configs/T1042RDB_PI_NAND_defconfig
+++ b/configs/T1042RDB_PI_NAND_defconfig
@@ -4,6 +4,7 @@
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="PPC_T1042,T1042RDB_PI,RAMBOOT_PBL,SPL_FSL_PBL,NAND"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y