RDMA/core: Create and destroy counters in the ib_core

Move allocation and destruction of counters under ib_core responsibility

Link: https://lore.kernel.org/r/20200630101855.368895-2-leon@kernel.org


Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>