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_SDCARD_DDRCLK133_defconfig b/configs/BSC9132QDS_SDCARD_DDRCLK133_defconfig
index 04c43be..1862f0c 100644
--- a/configs/BSC9132QDS_SDCARD_DDRCLK133_defconfig
+++ b/configs/BSC9132QDS_SDCARD_DDRCLK133_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_BSC9132QDS=y
 CONFIG_SYS_EXTRA_OPTIONS="BSC9132QDS,SDCARD,SYS_CLK_100_DDR_133"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y