RDMA/mlx5: Add support for 1600_8x lane speed

RDMA/mlx5: Add support for 1600_8x lane speed

Add a check for 1600G_8X link speed when querying PTYS and report it
back correctly when needed.

While at it, adjust mlx5 function which maps the speed rate from IB
spec values to internal driver values to be able to handle speeds
up to 1600Gbps.

Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Link: https://patch.msgid.link/20251120-speed-8-v1-2-e6a7efef8cb8@nvidia.com
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Leon Romanovsky <leon@kernel.org>