net/mlx5e: Cleanup attach encap function

Remove the tunnel info argument which we can get from the other args.
Also reorder the args to have input args first and output args later.

This patch doesn't change functionality.

Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>