Acceptable to propose handling ethtool flow-type

[clarkek]

I wanted to use a programmatic way to access the rx flow classification --config-nfc flow-type rules.. It appears to me netlink is not implemented for these rules, but the suitable ethtool handling is there (ETHTOOL_SRXCLSRLINS etc.) .. Would it be acceptable to submit PR add the handling for these features in this library as an alternative.

Perhaps there is a way to use the existing method without patching though as a test for temp use though.?