Legacy ixgbe driver update, including:
- Support for X553 (Denverton) devices.
- Initialization code refactoring.
- ixgbe-specific netmap code moved to ixgbe folder (but not removed from dev/netmap/).
- VF driver full split. Some cleanup can be had due to redundant code, but this split goes inline with the refactoring.
NOTE: This is to be applied on the 10-STABLE tree (and not HEAD). The idea is that many of these changes will be ported to the iflib version of ixgbe. The legacy version residing in HEAD may or may not be updated at a later time. For HEAD, our focus will mainly be on the iflib driver.