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/P1010RDB-PB_NAND_SECBOOT_defconfig b/configs/P1010RDB-PB_NAND_SECBOOT_defconfig
index b5b04d4..51286af 100644
--- a/configs/P1010RDB-PB_NAND_SECBOOT_defconfig
+++ b/configs/P1010RDB-PB_NAND_SECBOOT_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_P1010RDB=y
 CONFIG_SYS_EXTRA_OPTIONS="P1010RDB_PB,NAND_SECBOOT,SECURE_BOOT"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y