sd: update the bdev size in sd_revalidate_disk

[ Upstream commit b200e38c ]

This avoids the extra call to revalidate_disk_size in sd_rescan and
is otherwise a no-op because the size did not change, or we are in
the probe path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Stable-dep-of: 74363ec6 ("zram: fix uninitialized ZRAM not releasing backing device")
Signed-off-by: Sasha Levin <sashal@kernel.org>