configs: sama5d2_xplained: Add defconfig for ENV/boot from eMMC

This adds a defconfig for sama5d2_xplained board to get environment from
eMMC. The defconfig is made from sama5d2_xplained_mmc_defconfig, with
'bootcmd' and 'bootargs' changed to kernel, device-tree and rootfs from
eMMC. The environment is expected to be found in eMMC's FAT
partition.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
diff --git a/include/configs/sama5d2_xplained.h b/include/configs/sama5d2_xplained.h
index 92f7f0d..2cec1c7 100644
--- a/include/configs/sama5d2_xplained.h
+++ b/include/configs/sama5d2_xplained.h
@@ -36,8 +36,8 @@
 /* bootstrap + u-boot + env in sd card */
 #undef CONFIG_BOOTCOMMAND
 
-#define CONFIG_BOOTCOMMAND	"fatload mmc 1:1 0x21000000 at91-sama5d2_xplained.dtb; " \
-				"fatload mmc 1:1 0x22000000 zImage; " \
+#define CONFIG_BOOTCOMMAND	"fatload mmc " CONFIG_ENV_FAT_DEVICE_AND_PART " 0x21000000 at91-sama5d2_xplained.dtb; " \
+				"fatload mmc " CONFIG_ENV_FAT_DEVICE_AND_PART " 0x22000000 zImage; " \
 				"bootz 0x22000000 - 0x21000000"
 
 #elif CONFIG_SPI_BOOT