ethtool: support Forward Error Correction(fec)
Introducing support of ethtool FEC mode:
D-BUS API: fec-mode: uint32_t.
Keyfile:
[ethtool]
fec-mode=<uint32_t>nmcli: ethtool.fec-mode allowing values are any combination of:
- auto
- off
- rs
- baser
- llrs