- merge ifdi_tx_structures_free and ifdi_rx_structures_free in to
  ifdi_qset_structures_free
- rename iflib_txrx_structures_{setup, free} to
  iflib_qset_structures_{setup, free}
- remove ifdef'ed out polling code
- add TOE4, TSO6, and VLAN_MTU capability options
Day 2 of cxgb conversions
- Implement shared context configuration functions making
  state management strictly per-port where possible