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-PA_SPIFLASH_defconfig b/configs/P1010RDB-PA_SPIFLASH_defconfig
index 789ab8e..fc4afce 100644
--- a/configs/P1010RDB-PA_SPIFLASH_defconfig
+++ b/configs/P1010RDB-PA_SPIFLASH_defconfig
@@ -4,6 +4,7 @@
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="P1010RDB_PA,SPIFLASH"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y