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/minnowmax_defconfig b/configs/minnowmax_defconfig
index 21dbd87..37c07c1 100644
--- a/configs/minnowmax_defconfig
+++ b/configs/minnowmax_defconfig
@@ -20,6 +20,10 @@
 CONFIG_OF_CONTROL=y
 CONFIG_CPU=y
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_GIGADEVICE=y
+CONFIG_SPI_FLASH_MACRONIX=y
+CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_DM_ETH=y
 CONFIG_DM_PCI=y
 CONFIG_DM_RTC=y