load_multiboot(): get_image_size() returns int

Do not store return of get_image_size() in a uint32_t as it makes it
impossible to detect error returns from get_image_size.
Signed-off-by: NJes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

hw/multiboot.c

@@ -252,7 +252,7 @@ int load_multiboot(void *fw_cfg,
 
         do {
             char *next_space;
-            uint32_t mb_mod_length;
+            int mb_mod_length;
             uint32_t offs = mbs.mb_buf_size;
 
             next_initrd = strchr(initrd_filename, ',');