e1000: Clean up igb_txrx

[kbowling]

Summary

The intention here is to reduce differences with D30072. The main functional change is logical simplification in igb_rx_checksum.

Test Plan

Tested on I210 lagg with iperf3 etc

[gallatin]

sys/dev/e1000/igb_txrx.c

530

Maybe this is also worth a __predict_false()

534

I would not use a __predict here, as there is no v6 l3 checksum, so I assume that v6 packets would take the unpredicted path, and be penalized.

[kbowling]

Thanks for catching those mistakes. Can you take a look, I'm happy with this at the moment.

[markj]

Looks ok to me aside from the comments.

sys/dev/e1000/igb_txrx.c

494

This assignment isn't needed.

544

Indentation here should be by four spaces.