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.h b/tools/mkimage.h
index 9033a7d..d109d40 100644
--- a/tools/mkimage.h
+++ b/tools/mkimage.h
@@ -143,5 +143,6 @@
 void init_imx_image_type (void);
 void init_default_image_type (void);
 void init_fit_image_type (void);
+void init_ubl_image_type(void);
 
 #endif /* _MKIIMAGE_H_ */