net/mlx5e: Profile specific stats groups

Attach stats groups array to the profiles and make the stats utility
functions (get_num, update, fill, fill_strings) generic and use the
profile->stats_grps rather the hardcoded NIC stats groups.

This will allow future extension to have per profile stats groups.

In this patch mlx5e NIC and IPoIB will still share the same stats
groups.

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>