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_NAND_defconfig b/configs/P1022DS_NAND_defconfig
index e33da33..ef08a9e 100644
--- a/configs/P1022DS_NAND_defconfig
+++ b/configs/P1022DS_NAND_defconfig
@@ -5,6 +5,7 @@
 CONFIG_TPL=y
 CONFIG_SYS_EXTRA_OPTIONS="NAND"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y