tools: MediaTek: add MTK boot header generation to mkimage

This patch adds support for MTK boot image generation.

Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/Makefile b/tools/Makefile
index 3c0521f..c93d17a 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -116,6 +116,7 @@
 			$(LIBFDT_OBJS) \
 			gpimage.o \
 			gpimage-common.o \
+			mtk_image.o \
 			$(RSA_OBJS-y)
 
 dumpimage-objs := $(dumpimage-mkimage-objs) dumpimage.o