net/sfc: use default FEC mode
net/sfc: use default FEC mode

All FEC modes are supported and allowed, but none are explicitly
requested.

This effectively means that FEC mode is determined solely form cable
requirements and link partner capabilities / requirements.

Signed-off-by: Andrew Rybchenko <ac94ab2a8fe9a9a087f6e24dcbc16626b52c07e8@solarflare.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk