net: thunderx: Leave serdes lane config on 81/83xx to firmware

For DLMs and SLMs on 80/81/83xx, many lane configurations
across different boards are coming up. Also kernel doesn't have
any way to identify board type/info and since firmware does,
just get rid of figuring out lane to serdes config and take
whatever has been programmed by low level firmware.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>