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/BSC9132QDS_SPIFLASH_DDRCLK100_SECURE_defconfig b/configs/BSC9132QDS_SPIFLASH_DDRCLK100_SECURE_defconfig
index 2d885c7..5173a5b 100644
--- a/configs/BSC9132QDS_SPIFLASH_DDRCLK100_SECURE_defconfig
+++ b/configs/BSC9132QDS_SPIFLASH_DDRCLK100_SECURE_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_BSC9132QDS=y
 CONFIG_SYS_EXTRA_OPTIONS="BSC9132QDS,SPIFLASH,SYS_CLK_100_DDR_100,SECURE_BOOT"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y