IB/mlx5: Verify that Q counters are supported

Make sure that the Q counters are supported by the FW before trying
to allocate/deallocte them, this will avoid driver load failure when
they aren't supported by the FW.

Fixes: 0837e86a ('IB/mlx5: Add per port counters')
Cc: <stable@vger.kernel.org> # v4.7+
Signed-off-by: Kamal Heib <kamalh@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>