Hardware Counters for KNET interfaces

[KanjiMonster]

Currently any hardware packet counters are hidden within the Broadcom SDK. It would be nice if these counters could be exposed via standard ethtool interfaces.

This could be done the following way:

• Modify the KNET kernel interface with an function to update counters for created interfaces.
• Modify the KNET kernel module to expose those counters.
• Modify the SDK or OF-DPA to register a callback for counter updates in the SDK, and push the updated counters into the KNET kernel driver.