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/imagetool.c b/tools/imagetool.c
index 29d2189..da72115 100644
--- a/tools/imagetool.c
+++ b/tools/imagetool.c
@@ -45,6 +45,8 @@
 	init_ubl_image_type();
 	/* Init Davinci AIS support */
 	init_ais_image_type();
+	/* Init TI Keystone boot image generation/list support */
+	init_gpimage_type();
 }
 
 /*