zram_drv: update for backing dev info changes

A previous commit made the bdi embedded in the request queue
a pointer, but neglected to fixup zram. Fix it up.

Fixes: dc3b17cc ("block: Use pointer to backing_dev_info from request_queue")
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/zram/zram_drv.c

@@ -117,7 +117,7 @@ static void zram_revalidate_disk(struct zram *zram)
 {
 	revalidate_disk(zram->disk);
 	/* revalidate_disk reset the BDI_CAP_STABLE_WRITES so set again */
-	zram->disk->queue->backing_dev_info.capabilities |=
+	zram->disk->queue->backing_dev_info->capabilities |=
 		BDI_CAP_STABLE_WRITES;
 }