net/mlx5: save bonding member ports information

net/mlx5: save bonding member ports information

Since kernel bonding netdev doesn't provide statistics counter that
reflects all member ports, PMD has to manually summarize counters from
each member ports.

As a preparation, this patch collects bonding member port information
and saves to shared context data.

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>