mkimage: Add Kirkwood Boot Image support (kwbimage)

This patch adds support for "kwbimage" (Kirkwood Boot Image)
image types to the mkimage code.

For details refer to docs/README.kwbimage

This patch is tested with Sheevaplug board

Signed-off-by: Prafulla Wadaskar <prafulla@marvell.com>
Acked-by: Ron Lee <ron@debian.org>

Signed-off-by: Prafulla Wadaskar <prafulla@marvell.com>
diff --git a/tools/mkimage.h b/tools/mkimage.h
index 96f2ef8..ec67336 100644
--- a/tools/mkimage.h
+++ b/tools/mkimage.h
@@ -139,6 +139,7 @@
  *
  * Supported image types init functions
  */
+void init_kwb_image_type (void);
 void init_default_image_type (void);
 void init_fit_image_type (void);