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_SPIFLASH_SECBOOT_defconfig b/configs/P1010RDB-PB_SPIFLASH_SECBOOT_defconfig
index e4d45a7..d3d9e49 100644
--- a/configs/P1010RDB-PB_SPIFLASH_SECBOOT_defconfig
+++ b/configs/P1010RDB-PB_SPIFLASH_SECBOOT_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_P1010RDB=y
 CONFIG_SYS_EXTRA_OPTIONS="P1010RDB_PB,SPIFLASH,SECURE_BOOT"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y