md: call __md_stop_writes in md_stop

From the link [1], we can see raid1d was running even after the path
raid_dtr -> md_stop -> __md_stop.

Let's stop write first in destructor to align with normal md-raid to
fix the KASAN issue.

[1]. https://lore.kernel.org/linux-raid/CAPhsuW5gc4AakdGNdF8ubpezAuDLFOYUO_sfMZcec6hQFm8nhg@mail.gmail.com/T/#m7f12bf90481c02c6d2da68c64aeed4779b7df74a

Fixes: 48df498d ("md: move bitmap_destroy to the beginning of __md_stop")
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Song Liu <song@kernel.org>

drivers/md/md.c

@@ -6261,6 +6261,7 @@ void md_stop(struct mddev *mddev)
 	/* stop the array and free an attached data structures.
 	 * This is called from dm-raid
 	 */
+	__md_stop_writes(mddev);
 	__md_stop(mddev);
 	bioset_exit(&mddev->bio_set);
 	bioset_exit(&mddev->sync_set);