mkimage: add UBL header support for booting davinci cpus

creating an u-boot.ubl file, which contains the UBL Header
needed for booting from NAND with the RBL from TI. For more
information read doc/README.ublimage.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/tools/mkimage.c b/tools/mkimage.c
index 60f7263..7215d0f 100644
--- a/tools/mkimage.c
+++ b/tools/mkimage.c
@@ -158,6 +158,8 @@
 	init_fit_image_type ();
 	/* Init Default image generation/list support */
 	init_default_image_type ();
+	/* Init Davinci UBL support */
+	init_ubl_image_type();
 
 	params.cmdname = *argv;
 	params.addr = params.ep = 0;