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/ls1021atwr_qspi_defconfig b/configs/ls1021atwr_qspi_defconfig
index c0c8f3a..0c71df6 100644
--- a/configs/ls1021atwr_qspi_defconfig
+++ b/configs/ls1021atwr_qspi_defconfig
@@ -8,6 +8,8 @@
 CONFIG_OF_CONTROL=y
 CONFIG_DM=y
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_ATMEL=y
+CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y