tools: mkimage: add support for gpimage format

This patch add support for gpimage format as a preparatory
patch for porting u-boot for keystone2 devices and is
based on omapimage format. It re-uses gph header to store the
size and loadaddr as done in omapimage.c

Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Acked-by: Tom Rini <trini@ti.com>
diff --git a/tools/Makefile b/tools/Makefile
index 097cc1d..911ad43 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -73,6 +73,8 @@
 			crc32.o \
 			default_image.o \
 			fit_image.o \
+			gpimage.o \
+			gpimage-common.o \
 			image-fit.o \
 			image-host.o \
 			image.o \