net/mlx5e: Change parse attr struct to accommodate multiple tunnel infos

Currently the driver can support only a single TC tunnel_set action.
Change the tunnel info fields to arrays, as a pre-step to support
multiple encapsulations for a single flow, with no functional change.

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