This adds bhnd-compatible implementations of bus_(read|write|set)_(1|2|4) APIs,
and upgrades the SPROM parsing code to use bhnd_bus_read_region_stream_2().
This a precursor to bridge support for resource adjustment and the new
ChipCommon bus support.
Tested:
* Tested against BCM4331
* Kernel build verified via tinderbox.
Submitted by: Landon Fuller <landonf@landonf.org>
Differential Revision: https://reviews.freebsd.org/D6469