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_36BIT_SDCARD_defconfig b/configs/P1010RDB-PA_36BIT_SDCARD_defconfig
index 974dadb..d656b21 100644
--- a/configs/P1010RDB-PA_36BIT_SDCARD_defconfig
+++ b/configs/P1010RDB-PA_36BIT_SDCARD_defconfig
@@ -4,6 +4,7 @@
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="P1010RDB_PA,36BIT,SDCARD"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y