rbd: fix compile error

Commit 787e4a85 [block: Add options QDict to bdrv_file_open() prototypes] didn't
update rbd.c accordingly.

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NLiu Yuan <tailai.ly@taobao.com>
Reviewed-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

block/rbd.c

@@ -441,7 +441,8 @@ static int qemu_rbd_aio_flush_cb(void *opaque)
     return (s->qemu_aio_count > 0);
 }
 
-static int qemu_rbd_open(BlockDriverState *bs, const char *filename, int flags)
+static int qemu_rbd_open(BlockDriverState *bs, const char *filename,
+                         QDict *options, int flags)
 {
     BDRVRBDState *s = bs->opaque;
     char pool[RBD_MAX_POOL_NAME_SIZE];