NFS: Fix up the declaration of nfs4_restart_rpc when NFSv4 not configured

Also rename it: it is used in generic code, and so should not have a 'nfs4'
prefix.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 1064c91..6da3d3f 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -83,7 +83,7 @@
 	struct inode *dir = data->dir;
 
 	if (!NFS_PROTO(dir)->unlink_done(task, dir))
-		nfs4_restart_rpc(task, NFS_SERVER(dir)->nfs_client);
+		nfs_restart_rpc(task, NFS_SERVER(dir)->nfs_client);
 }
 
 /**