[bhnd] Centralize fetching of board information

Centralizes fetching of board information (vendor, type, revision, etc),
and adds support for matching quirks against board identification info.

• Adds a BHND_BUS_READ_BOARD_INFO(), allowing bhnd bus/bus parent(s) to handle implementation-specific fetching of board info.
• Integrates board type constants from the latest Broadcom ISC-licensed bcmdevs.h included in dd-wrt's Broadcom driver source drops.
• Adds support for matching on chip/board quirks to bhnd_device_quirks()/ bhnd_chip_quirks().
• Use the new board/chip quirk matching to match Apple devices that failed to set BFL2_PCIEWAR_OVR in SROM.

Submitted by: Landon Fuller <landonf@landonf.org>
Differential Revision: https://reviews.freebsd.org/D6361