NFS: exit_nfs_v4() shouldn't be an __exit function

... yet.  Right now, init_nfs() is calling this function if an error is
encountered when loading the nfs module.  An __exit function can't be
called from one declared as __init.
Signed-off-by: NBryan Schumaker <bjschuma@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4super.c

@@ -352,7 +352,7 @@ int __init init_nfs_v4(void)
 	return err;
 }
 
-void __exit exit_nfs_v4(void)
+void exit_nfs_v4(void)
 {
 	unregister_filesystem(&nfs4_fs_type);
 	nfs4_unregister_sysctl();