mkimage: Add Freescale imx Boot Image support (imximage)

This patch adds support for "imximage" (MX Boot Image)
to the mkimage utility. The imximage is used on the Freescales's
MX.25, MX.35 and MX.51 processors.

Further details under doc/README.imximage.

This patch was tested on a Freescale mx51evk board.

Signed-off-by: Stefano Babic <sbabic@denx.de>
diff --git a/include/image.h b/include/image.h
index acc553c..541cac9 100644
--- a/include/image.h
+++ b/include/image.h
@@ -156,6 +156,7 @@
 #define IH_TYPE_FILESYSTEM	7	/* Filesystem Image (any type)	*/
 #define IH_TYPE_FLATDT		8	/* Binary Flat Device Tree Blob	*/
 #define IH_TYPE_KWBIMAGE	9	/* Kirkwood Boot Image		*/
+#define IH_TYPE_IMXIMAGE	10	/* Freescale IMXBoot Image	*/
 
 /*
  * Compression Types