ARM: at91: sama5d3xek: save enviroment as a FAT file in MMC card

This patch will save U-Boot environment as a file: uboot.env, in FAT partition
instead of in raw sector of MMC card.

This make us easier to manage the environment file.
Signed-off-by: NJosh Wu <josh.wu@atmel.com>
Acked-by: NBo Shen <voice.shen@atmel.com>

include/configs/sama5d3xek.h

@@ -191,6 +191,7 @@
 
 #if defined(CONFIG_CMD_USB) || defined(CONFIG_CMD_MMC)
 #define CONFIG_CMD_FAT
+#define CONFIG_FAT_WRITE
 #endif
 
 #define CONFIG_SYS_LOAD_ADDR			0x22000000 /* load address */
@@ -215,13 +216,14 @@
 				"bootm 0x22000000 - 0x21000000"
 #elif CONFIG_SYS_USE_MMC
 /* bootstrap + u-boot + env in sd card */
-#define CONFIG_ENV_IS_IN_MMC
-#define CONFIG_ENV_OFFSET	0x2000
-#define CONFIG_ENV_SIZE		0x1000
+#define CONFIG_ENV_IS_IN_FAT
+#define FAT_ENV_INTERFACE	"mmc"
+#define FAT_ENV_FILE		"uboot.env"
+#define FAT_ENV_DEVICE_AND_PART	"0"
+#define CONFIG_ENV_SIZE		0x4000
 #define CONFIG_BOOTCOMMAND	"fatload mmc 0:1 0x21000000 dtb; " \
 				"fatload mmc 0:1 0x22000000 uImage; " \
 				"bootm 0x22000000 - 0x21000000"
-#define CONFIG_SYS_MMC_ENV_DEV	0
 #else
 #define CONFIG_ENV_IS_NOWHERE
 #endif