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/birdland_bav335b_defconfig b/configs/birdland_bav335b_defconfig
index 601370e..2ed64f6 100644
--- a/configs/birdland_bav335b_defconfig
+++ b/configs/birdland_bav335b_defconfig
@@ -8,4 +8,5 @@
 CONFIG_CMD_GPIO=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_SYS_NS16550=y