block: vmdk - fixed sizeof() error

The size compared should be PATH_MAX, rather than sizeof(char *).
Reported-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Message-id: 46d873261433f4527e88885582f96942d61758d6.1423592487.git.jcody@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

block/vmdk.c

@@ -843,8 +843,7 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
         }
 
         extent_path = g_malloc0(PATH_MAX);
-        path_combine(extent_path, sizeof(extent_path),
-                desc_file_path, fname);
+        path_combine(extent_path, PATH_MAX, desc_file_path, fname);
         extent_file = NULL;
         ret = bdrv_open(&extent_file, extent_path, NULL, NULL,
                         bs->open_flags | BDRV_O_PROTOCOL, NULL, errp);