vexpress_ca9x4: Enable use of correct DTB file and restore EFI loader.

EFI was disabled in f95b8a4b5f64f because of the missing DTB file,
and indeed, the DTB file is required to load recent versions of GRUB
(2.04) correctly.

Signed-off-by: Kristian Amlie <kristian.amlie@northern.tech>
diff --git a/include/configs/vexpress_common.h b/include/configs/vexpress_common.h
index 7f215a6..e73658a 100644
--- a/include/configs/vexpress_common.h
+++ b/include/configs/vexpress_common.h
@@ -207,7 +207,8 @@
 			"devtmpfs.mount=0  vmalloc=256M\0" \
 		"bootflash=run flashargs; " \
 			"cp ${ramdisk_addr} ${ramdisk_addr_r} ${maxramdisk}; " \
-			"bootm ${kernel_addr} ${ramdisk_addr_r}\0"
+			"bootm ${kernel_addr} ${ramdisk_addr_r}\0" \
+		"fdtfile=" CONFIG_DEFAULT_FDT_FILE "\0"
 
 /* FLASH and environment organization */
 #define PHYS_FLASH_SIZE			0x04000000	/* 64MB */