imx: mx6sxsabresd: enable CONFIG_SPL_FAT_SUPPORT

Enable CONFIG_SPL_FAT_SUPPORT to load u-boot.img from FAT partition.
Signed-off-by: NPeng Fan <Peng.Fan@freescale.com>
Reviewed-by: NStefano Babic <sbabic@denx.de>

include/configs/mx6sxsabresd.h

@@ -15,6 +15,7 @@
 #ifdef CONFIG_SPL
 #define CONFIG_SPL_LIBCOMMON_SUPPORT
 #define CONFIG_SPL_MMC_SUPPORT
+#define CONFIG_SPL_FAT_SUPPORT
 #include "imx6_spl.h"
 #endif