net/mlx5e: Use netdev_info instead of pr_info

The next patch will pass the mlx5e_priv struct to the
modify_header_match_supported method. Use this opportunity to refactor
the existing pr_info call to a netdev_info call.

Signed-off-by: Oz Shlomo <ozsh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>