RDMA: Fix return code check in rdma_set_cq_moderation

The proper return code is "-EOPNOTSUPP" when the modify_cq() callback is
not supported, all drivers should generate this and all users should check
for it when detecting not supported functionality.
Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com> (for mlx5)
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx5/cq.c

@@ -1184,7 +1184,7 @@ int mlx5_ib_modify_cq(struct ib_cq *cq, u16 cq_count, u16 cq_period)
 	int err;
 
 	if (!MLX5_CAP_GEN(dev->mdev, cq_moderation))
-		return -ENOSYS;
+		return -EOPNOTSUPP;
 
 	if (cq_period > MLX5_MAX_CQ_PERIOD)
 		return -EINVAL;

drivers/infiniband/ulp/ipoib/ipoib_ethtool.c

@@ -102,7 +102,7 @@ static int ipoib_set_coalesce(struct net_device *dev,
 	ret = rdma_set_cq_moderation(priv->recv_cq,
 				     coal->rx_max_coalesced_frames,
 				     coal->rx_coalesce_usecs);
-	if (ret && ret != -ENOSYS) {
+	if (ret && ret != -EOPNOTSUPP) {
 		ipoib_warn(priv, "failed modifying CQ (%d)\n", ret);
 		return ret;
 	}