net/mlx5: delete dead code in mlx5_esw_unlock()

Smatch complains about this function:

    drivers/net/ethernet/mellanox/mlx5/core/eswitch.c:2000 mlx5_esw_unlock()
    warn: inconsistent returns '&esw->mode_lock'.

Before commit ec2fa47d ("net/mlx5: Lag, use lag lock") there
used to be a matching mlx5_esw_lock() function and the lock and
unlock functions were symmetric.  But now we take the lock
unconditionally and must unlock unconditionally as well.

As near as I can tell this is dead code and can just be deleted.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/eswitch.c

@@ -1995,8 +1995,6 @@ int mlx5_esw_try_lock(struct mlx5_eswitch *esw)
  */
 void mlx5_esw_unlock(struct mlx5_eswitch *esw)
 {
-	if (!mlx5_esw_allowed(esw))
-		return;
 	up_write(&esw->mode_lock);
 }