common/mlx5: disable relaxed ordering in unsuitable CPUs

common/mlx5: disable relaxed ordering in unsuitable CPUs

Relaxed ordering is a PCI optimization that enables reordering
reads/writes in order to improve performance.

Relaxed ordering was enabled for all processors causing
a degradation in performance in Haswell and Broadwell processors
that don't support this optimization.

In order to avoid that we check if the processor is Haswell
or Broadwell and if so we disable relaxed ordering.

Signed-off-by: Shiri Kuzin <shirik@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>