Introduce initial support for Cavium's ThunderX networking interface

• The driver consists of three main componens: PF, VF, BGX
• Requires appropriate entries in DTS and MDIO driver
• Supports only FDT configuration
• Multiple Tx queues and single Rx queue supported
• No RSS, HW checksum and TSO support
• No more than 8 queues per-IF (only one Queue Set per IF)
• HW statistics enabled
• Works in all available MAC modes (1,10,20,40G)
• Style converted to BSD according to style(9)
• The code brings lmac_if interface used by the BGX driver to update its logical MACs state.

Obtained from: Semihalf
Sponsored by: The FreeBSD Foundation