net/mlx5e: Store all XFRM SAs in Xarray

Instead of performing custom hash calculations, rely on FW that returns
unique identifier to every created SA. That identifier is Xarray ready,
which provides better semantic with efficient access.

In addition, store both TX and RX SAs to allow correlation between event
generated by HW when limits are armed and XFRM states.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>