RDMA/counters: Properly implement PID checks

RDMA/counters: Properly implement PID checks

"Auto" configuration mode is called for visible in that PID
namespace and it ensures that all counters and QPs are coexist
in the same namespace and belong to same PID.

Fixes: 99fa331dc862 ("RDMA/counter: Add "auto" configuration mode support")
Reviewed-by: Mark Zhang <markz@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Link: https://lore.kernel.org/r/20190815083834.9245-3-leon@kernel.org
Signed-off-by: Doug Ledford <dledford@redhat.com>