tools: moved code common to all image tools to a separated module.

In order to avoid duplicating code and keep only one point of modification,
the functions, structs and defines useful for "dumpimage" were moved from
"mkimage" to a common module called "imagetool".

This modification also weakens the coupling between image types (FIT, IMX, MXS,
and so on) and image tools (mkimage and dumpimage). Any tool may initialize the
"imagetool" through register_image_tool() function, while the image types
register themselves within an image tool using the register_image_type()
function:

                                                      +---------------+
                                               +------|   fit_image   |
 +--------------+          +-----------+       |      +---------------+
 |    mkimage   |--------> |           | <-----+
 +--------------+          |           |              +---------------+
                           | imagetool | <------------|    imximage   |
 +--------------+          |           |              +---------------+
 |  dumpimage   |--------> |           | <-----+
 +--------------+          +-----------+       |      +---------------+
                                               +------| default_image |
                                                      +---------------+

          register_image_tool()           register_image_type()

Also, the struct "mkimage_params" was renamed to "image_tool_params" to make
clear its general purpose.

Signed-off-by: Guilherme Maciel Ferreira <guilherme.maciel.ferreira@gmail.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/pblimage.c b/tools/pblimage.c
index bac5faf..ef3d7f6 100644
--- a/tools/pblimage.c
+++ b/tools/pblimage.c
@@ -3,7 +3,7 @@
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */
-#include "mkimage.h"
+#include "imagetool.h"
 #include <image.h>
 #include "pblimage.h"
 
@@ -242,7 +242,7 @@
 	}
 }
 
-void pbl_load_uboot(int ifd, struct mkimage_params *params)
+void pbl_load_uboot(int ifd, struct image_tool_params *params)
 {
 	FILE *fp_uboot;
 	int size;
@@ -281,7 +281,7 @@
 }
 
 static int pblimage_verify_header(unsigned char *ptr, int image_size,
-			struct mkimage_params *params)
+			struct image_tool_params *params)
 {
 	struct pbl_header *pbl_hdr = (struct pbl_header *) ptr;
 
@@ -308,7 +308,7 @@
 }
 
 static void pblimage_set_header(void *ptr, struct stat *sbuf, int ifd,
-				struct mkimage_params *params)
+				struct image_tool_params *params)
 {
 	/*nothing need to do, pbl_load_uboot takes care of whole file. */
 }
@@ -327,5 +327,5 @@
 void init_pbl_image_type(void)
 {
 	pbl_size = 0;
-	mkimage_register(&pblimage_params);
+	register_image_type(&pblimage_params);
 }