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/T1042D4RDB_SECURE_BOOT_defconfig b/configs/T1042D4RDB_SECURE_BOOT_defconfig
index ca1d83c..f856f7d 100644
--- a/configs/T1042D4RDB_SECURE_BOOT_defconfig
+++ b/configs/T1042D4RDB_SECURE_BOOT_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_T104XRDB=y
 CONFIG_SYS_EXTRA_OPTIONS="PPC_T1042,T1042D4RDB,T104XD4RDB,SYS_FSL_DDR4,SECURE_BOOT"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y