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/P1022DS_36BIT_SPIFLASH_defconfig b/configs/P1022DS_36BIT_SPIFLASH_defconfig
index 41d14f4..130b7cf 100644
--- a/configs/P1022DS_36BIT_SPIFLASH_defconfig
+++ b/configs/P1022DS_36BIT_SPIFLASH_defconfig
@@ -4,6 +4,7 @@
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="36BIT,SPIFLASH"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y