memstick/ms_block: Add check for alloc_ordered_workqueue

As the alloc_ordered_workqueue may return NULL pointer, it should be better
to add check for the return value. Moreover, the msb->io_queue should be
freed if error occurs later.

Fixes: 0ab30494bc4f ("memstick: add support for legacy memorysticks")
Signed-off-by: Jiasheng Jiang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/memstick/core/ms_block.c

···
 	dbg("Set total disk size to %lu sectors", capacity);
 
 	msb->io_queue = alloc_ordered_workqueue("ms_block", WQ_MEM_RECLAIM);
+	if (!msb->io_queue) {
+		rc = -ENOMEM;
+		goto out_cleanup_disk;
+	}
+
 	INIT_WORK(&msb->io_work, msb_io_work);
 	sg_init_table(msb->prealloc_sg, MS_BLOCK_MAX_SEGS+1);
 
···
 	msb_start(card);
 	rc = device_add_disk(&card->dev, msb->disk, NULL);
 	if (rc)
-		goto out_cleanup_disk;
+		goto out_destroy_workqueue;
 	dbg("Disk added");
 	return 0;
 
+out_destroy_workqueue:
+	destroy_workqueue(msb->io_queue);
 out_cleanup_disk:
 	put_disk(msb->disk);
 out_free_tag_set: