nfs: fix stub return type warnings

Fix numerous repeated warnings by making the stub function
void instead of non-void:

fs/nfs/nfs4_fs.h: In function 'nfs4_unregister_sysctl':
fs/nfs/nfs4_fs.h:385:1: warning: no return statement in function returning non-void

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc:	Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index b1ecacd..5511690 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -380,7 +380,7 @@
 	return 0;
 }
 
-static inline int nfs4_unregister_sysctl(void)
+static inline void nfs4_unregister_sysctl(void)
 {
 }
 #endif