net/mlx5: Fix UAF in mlx5_eswitch_cleanup()

mlx5_eswitch_cleanup() is using esw right after freeing it for
releasing devlink_param.
Fix it by releasing the devlink_param before freeing the esw, and
adjust the create function accordingly.

Fixes: 3f908403 ("net/mlx5: Move esw multiport devlink param to eswitch code")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Automatic Verification <verifier@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>