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/zynq_zed_defconfig b/configs/zynq_zed_defconfig
index 15efb19..f603bb3 100644
--- a/configs/zynq_zed_defconfig
+++ b/configs/zynq_zed_defconfig
@@ -12,4 +12,7 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_SPANSION=y
+CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_ZYNQ_QSPI=y