net/mlx5e: Fix condition when retrieving PTP-rqn

When activating the PTP-RQ, redirect the RQT from drop-RQ to PTP-RQ.
Use mlx5e_channels_get_ptp_rqn to retrieve the rqn. This helper returns
a boolean (not status), hence caller should consider return value 0 as a
fail. Change the caller interpretation of the return value.

Fixes: 43ec0f41 ("net/mlx5e: Hide all implementation details of mlx5e_rx_res")
Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/rx_res.c

@@ -572,7 +572,7 @@ void mlx5e_rx_res_channels_activate(struct mlx5e_rx_res *res, struct mlx5e_chann
 	if (res->features & MLX5E_RX_RES_FEATURE_PTP) {
 		u32 rqn;
 
-		if (mlx5e_channels_get_ptp_rqn(chs, &rqn))
+		if (!mlx5e_channels_get_ptp_rqn(chs, &rqn))
 			rqn = res->drop_rqn;
 
 		err = mlx5e_rqt_redirect_direct(&res->ptp.rqt, rqn);