ice: Accept LAG netdevs in bridge offloads

Allow LAG interfaces to be used in bridge offload using
netif_is_lag_master. In this case, search for ice netdev in
the list of LAG's lower devices.

Reviewed-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>