nfsd: declare several functions of nfs4callback as static

setup_callback_client(), nfsd4_release_cb() and nfsd4_process_cb_update()
do not have users outside the translation unit. Let's declare it as
static.
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4callback.c

@@ -473,7 +473,8 @@ static int max_cb_time(void)
 /* Reference counting, callback cleanup, etc., all look racy as heck.
  * And why is cl_cb_set an atomic? */
 
-int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
+static int setup_callback_client(struct nfs4_client *clp,
+		struct nfs4_cb_conn *conn)
 {
 	struct rpc_timeout	timeparms = {
 		.to_initval	= max_cb_time(),
@@ -748,13 +749,13 @@ void nfsd4_shutdown_callback(struct nfs4_client *clp)
 	flush_workqueue(callback_wq);
 }
 
-void nfsd4_release_cb(struct nfsd4_callback *cb)
+static void nfsd4_release_cb(struct nfsd4_callback *cb)
 {
 	if (cb->cb_ops->rpc_release)
 		cb->cb_ops->rpc_release(cb);
 }
 
-void nfsd4_process_cb_update(struct nfsd4_callback *cb)
+static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
 {
 	struct nfs4_cb_conn conn;
 	struct nfs4_client *clp = cb->cb_clp;