net/rds: Use PTR_ERR instead of IS_ERR for rdsdebug()

If 'local_odp_mr->r_trans_private' is a error code,
it is better to print the error code than to print
the value of IS_ERR().
Signed-off-by: Li Qiong <liqiong@nfschina.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/rdma.c

@@ -742,7 +742,7 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
 					NULL, 0, rs, &local_odp_mr->r_key, NULL,
 					iov->addr, iov->bytes, ODP_VIRTUAL);
 			if (IS_ERR(local_odp_mr->r_trans_private)) {
-				ret = IS_ERR(local_odp_mr->r_trans_private);
+				ret = PTR_ERR(local_odp_mr->r_trans_private);
 				rdsdebug("get_mr ret %d %p\"", ret,
 					 local_odp_mr->r_trans_private);
 				kfree(local_odp_mr);