mkimage: Allow a FIT to include an image of any type

At present FIT images are set up by providing a device tree source file
which is a file with a .its extension. We want to support automatically
creating this file based on the image supplied to mkimage. This means that
even though the final file type is always IH_TYPE_FLATDT, the image inside
may be something else.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/imagetool.h

@@ -61,6 +61,7 @@ struct image_tool_params {
 	int require_keys;	/* 1 to mark signing keys as 'required' */
 	int file_size;		/* Total size of output file */
 	int orig_file_size;	/* Original size for file before padding */
+	int fit_image_type;	/* Image type to put into the FIT */
 };
 
 /*