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/pcm051_rev1_defconfig b/configs/pcm051_rev1_defconfig
index d81b405..ce7c4bb 100644
--- a/configs/pcm051_rev1_defconfig
+++ b/configs/pcm051_rev1_defconfig
@@ -7,4 +7,5 @@
 CONFIG_CMD_GPIO=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_SYS_NS16550=y