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/P4080DS_SECURE_BOOT_defconfig b/configs/P4080DS_SECURE_BOOT_defconfig
index 3809c3d..92e1c1d 100644
--- a/configs/P4080DS_SECURE_BOOT_defconfig
+++ b/configs/P4080DS_SECURE_BOOT_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_P4080DS=y
 CONFIG_SYS_EXTRA_OPTIONS="SECURE_BOOT"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y