IB/mlx5: Update counter implementation for dual port RoCE

Update the counter interface for multiple ports. Some counter sets
always comes from the primary device.

Port specific counters should be accessed per mlx5_core_dev not always
through the IB master mdev.

Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>