NFSv4.1: nfs4_destroy_session must call rpc_destroy_waitqueue

There may still be timers active on the session waitqueues. Make sure
that we kill them before freeing the memory.

Cc: stable@vger.kernel.org # 3.12+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index dbb3e1f..860ad26 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -170,7 +170,7 @@
 void nfs40_shutdown_client(struct nfs_client *clp)
 {
 	if (clp->cl_slot_tbl) {
-		nfs4_release_slot_table(clp->cl_slot_tbl);
+		nfs4_shutdown_slot_table(clp->cl_slot_tbl);
 		kfree(clp->cl_slot_tbl);
 	}
 }