ipc: mqueue: fix possible memory leak in init_mqueue_fs()

commit db7cfc3 ("ipc: Free mq_sysctls if ipc namespace creation
failed")

Here's a similar memory leak to the one fixed by the patch above.
retire_mq_sysctls need to be called when init_mqueue_fs fails after
setup_mq_sysctls.

Fixes: dc55e35 ("ipc: Store mqueue sysctls in the ipc namespace")
Signed-off-by: Hangyu Hua <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Eric W. Biederman <[email protected]>

ipc/mqueue.c

@@ -1746,6 +1746,7 @@ static int __init init_mqueue_fs(void)
 	unregister_filesystem(&mqueue_fs_type);
 out_sysctl:
 	kmem_cache_destroy(mqueue_inode_cachep);
+	retire_mq_sysctls(&init_ipc_ns);
 	return error;
 }