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/common/image.c b/common/image.c
index 91954ac..0c601bb 100644
--- a/common/image.c
+++ b/common/image.c
@@ -143,6 +143,7 @@
 	{	IH_TYPE_INVALID,    NULL,	  "Invalid Image",	},
 	{	IH_TYPE_MULTI,	    "multi",	  "Multi-File Image",	},
 	{	IH_TYPE_OMAPIMAGE,  "omapimage",  "TI OMAP SPL With GP CH",},
+	{	IH_TYPE_PBLIMAGE,   "pblimage",   "Freescale PBL Boot Image",},
 	{	IH_TYPE_RAMDISK,    "ramdisk",	  "RAMDisk Image",	},
 	{	IH_TYPE_SCRIPT,     "script",	  "Script",		},
 	{	IH_TYPE_STANDALONE, "standalone", "Standalone Program", },