arm: mvebu: configs: turris_mox: add fdtfile default env variable

Add default fdtfile environment variable with value
marvell/armada-3720-turris-mox.dtb.

This can be useful for some boot scenarios.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/include/configs/turris_mox.h b/include/configs/turris_mox.h
index b148b16..9c021a1 100644
--- a/include/configs/turris_mox.h
+++ b/include/configs/turris_mox.h
@@ -89,6 +89,7 @@
 	"fdt_addr_r=0x4f00000\0"	\
 	"kernel_addr_r=0x5000000\0"	\
 	"ramdisk_addr_r=0x8000000\0"	\
+	"fdtfile=marvell/" CONFIG_DEFAULT_DEVICE_TREE ".dtb\0" \
 	"bootcmd_rescue=" TURRIS_MOX_BOOTCMD_RESCUE "\0" \
 	BOOTENV