[RFE] Support setting channels in ethtool options of NetworkManager

Description of problem:
Currently NetworkManager supports ethtool options to tune offloading, coalesce, pause frames and ring buffer.
Adding the support for setting channels (-L) would be good feature. One of our customer is requesting the same.

As of now, we are using dispatcher script to cater the use-case.
Should it be feasible to have native feature for setting ethtool channels ?

Eg : nmcli con mod <interface> ethtool.set-channels combined 4