block: don't skip empty device in in disk_uevent

Restore the previous behavior by using the correct flag for the whole device
("part0").

Fixes: 99dfc43e ("block: use ->bi_bdev for bio based I/O accounting")
Reported-by: John Stultz <john.stultz@linaro.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/genhd.c

@@ -476,7 +476,7 @@ void disk_uevent(struct gendisk *disk, enum kobject_action action)
 	struct disk_part_iter piter;
 	struct block_device *part;
 
-	disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
+	disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY_PART0);
 	while ((part = disk_part_iter_next(&piter)))
 		kobject_uevent(bdev_kobj(part), action);
 	disk_part_iter_exit(&piter);