powerpc/CoreNet: add tool to support pbl image build.

Provides a tool to build boot Image for PBL(Pre boot loader) which is
used on Freescale CoreNet SoCs, PBL can be used to load some instructions
and/or data for pre-initialization. The default output image is u-boot.pbl,
for more details please refer to doc/README.pblimage.

Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>
diff --git a/include/image.h b/include/image.h
index aa9daa2..e5f6649 100644
--- a/include/image.h
+++ b/include/image.h
@@ -164,6 +164,7 @@
 #define IH_TYPE_OMAPIMAGE	12	/* TI OMAP Config Header Image	*/
 #define IH_TYPE_AISIMAGE	13	/* TI Davinci AIS Image		*/
 #define IH_TYPE_KERNEL_NOLOAD	14	/* OS Kernel Image, can run from any load address */
+#define IH_TYPE_PBLIMAGE	15	/* Freescale PBL Boot Image	*/
 
 /*
  * Compression Types