RDMA/cma: Remove CM_ID statistics provided by rdma-cm module

Netlink statistics exported by rdma-cm never had any working user space
component published to the mailing list or to any open source
project. Canvassing various proprietary users, and the original requester,
we find that there are no real users of this interface.

This patch simply removes all occurrences of RDMA CM netlink in favour of
modern nldev implementation, which provides the same information and
accompanied by widely used user space component.

Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>