RDMA: Make counters destroy symmetrical

Change counters to return failure like any other verbs destroy, however
this flow shouldn't return error at all.

Link: https://lore.kernel.org/r/20200907120921.476363-10-leon@kernel.org


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