m25p80: add missing blk_attach_dev_nofail

Of the block devices that poked into -drive options via drive_get_next,
m25p80 was the only one who also did not attach itself to the BlockBackend.

Since sd does it, and all other devices go through a "drive" property,
with this change all block backends attached to the guest will have a
non-NULL result for blk_get_attached_dev().
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NPeter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 1429025387-11077-1-git-send-email-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

hw/block/m25p80.c

@@ -629,6 +629,7 @@ static int m25p80_init(SSISlave *ss)
     if (dinfo) {
         DB_PRINT_L(0, "Binding to IF_MTD drive\n");
         s->blk = blk_by_legacy_dinfo(dinfo);
+        blk_attach_dev_nofail(s->blk, s);
 
         /* FIXME: Move to late init */
         if (blk_read(s->blk, 0, s->storage,