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/bf561-acvilon_defconfig b/configs/bf561-acvilon_defconfig
index cb813ea..4a25d2e 100644
--- a/configs/bf561-acvilon_defconfig
+++ b/configs/bf561-acvilon_defconfig
@@ -6,5 +6,6 @@
 CONFIG_CMD_GPIO=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_ATMEL=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
 CONFIG_LIB_RAND=y