This adds support for the NVRAM handling and the basic SPROM
hardware used on siba(4) and bcma(4) devices, including:
* SPROM directly attached to the PCI core, accessible via PCI configuration
space.
* SPROM attached to later ChipCommon cores.
* SPROM variables vended from the parent SoC bus (e.g. via a directly-attached
flash device).
Additional improvements to the NVRAM/SPROM interface will
be required, but this changeset stands alone as working
checkpoint.
Submitted by: Landon Fuller <landonf@landonf.org>
Reviewed by: Michael Zhilin <mizkha@gmail.com> (Broadcom MIPS support)
Differential Revision: https://reviews.freebsd.org/D6196
