IB/mlx5: Add counters create and destroy support

This patch implements the device counters create and destroy APIs and
introducing some internal management structures.

Downstream patches in this series will add the functionality to support
flow counters binding and reading.

Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Raed Salem <raeds@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>