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/lschlv2_defconfig b/configs/lschlv2_defconfig
index 9fd89a6..7264c2d 100644
--- a/configs/lschlv2_defconfig
+++ b/configs/lschlv2_defconfig
@@ -7,4 +7,5 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SYS_NS16550=y