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-PB_NOR_defconfig b/configs/P1010RDB-PB_NOR_defconfig
index 514ebed..c07fa85 100644
--- a/configs/P1010RDB-PB_NOR_defconfig
+++ b/configs/P1010RDB-PB_NOR_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_P1010RDB=y
 CONFIG_SYS_EXTRA_OPTIONS="P1010RDB_PB"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y