[new uImage] Define a API for image handling operations

- Add inline helper macros for basic header processing
- Move common non inline code common/image.c
- Replace direct header access with the API routines
- Rename IH_CPU_* to IH_ARCH_*

Signed-off-by: Marian Balakowicz <m8@semihalf.com>

common/cmd_doc.c

@@ -263,11 +263,11 @@ int do_docboot (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 
 	hdr = (image_header_t *)addr;
 
-	if (hdr->ih_magic == IH_MAGIC) {
+	if (image_check_magic (hdr)) {
 
 		print_image_hdr (hdr);
 
-		cnt = (ntohl(hdr->ih_size) + sizeof(image_header_t));
+		cnt = image_get_image_size (hdr);
 		cnt -= SECTORSIZE;
 	} else {
 		puts ("\n** Bad Magic Number **\n");