cbfstool/cbfs-mkstage.c: Change signature of parse_elf_to_xip_stage()

The dereferced parameter is never updated so passing a copy would work
too.

Change-Id: Ie36f64f55d4fc7034780116c28aaed65aa304d5e
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55792
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/cbfstool/cbfstool.c

@@ -1131,7 +1131,7 @@ static int cbfstool_convert_mkstage(struct buffer *buffer, uint32_t *offset,
 		 **/
 		*offset = convert_addr_space(param.image_region, *offset);
 
-		ret = parse_elf_to_xip_stage(buffer, &output, offset,
+		ret = parse_elf_to_xip_stage(buffer, &output, *offset,
 					     param.ignore_section,
 					     stageheader);
 	} else {