RDMA/nldev: Skip counter if port doesn't match

RDMA/nldev: Skip counter if port doesn't match

The counter resource should return -EAGAIN if it was requested for a
different port, this is similar to how QP works if the users provides a
port filter.

Otherwise port filtering in netlink will return broken counter nests.

Fixes: c4ffee7c9bdb ("RDMA/netlink: Implement counter dumpit calback")
Link: https://lore.kernel.org/r/20191020062800.8065-1-leon@kernel.org
Signed-off-by: Mark Zhang <markz@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>