nfs: Use PTR_ERR_OR_ZERO in 'nfs41_callback_up' function

Use 'PTR_ERR_OR_ZERO()' rather than 'IS_ERR(...) ? PTR_ERR(...) : 0'.
Signed-off-by: NGeyslan G. Bem <geyslan@gmail.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/callback.c

@@ -164,8 +164,7 @@ nfs41_callback_up(struct svc_serv *serv)
 		svc_xprt_put(serv->sv_bc_xprt);
 		serv->sv_bc_xprt = NULL;
 	}
-	dprintk("--> %s return %ld\n", __func__,
-		IS_ERR(rqstp) ? PTR_ERR(rqstp) : 0);
+	dprintk("--> %s return %d\n", __func__, PTR_ERR_OR_ZERO(rqstp));
 	return rqstp;
 }