Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFpseries:
Renovate and improve the AIM Open Firmware support:
- Add RTAS (Run-Time Abstraction Services) support, found on all IBM systems
and some Apple ones
- Improve support for 32-bit real mode Open Firmware systems
- Pull some more OF bits over from the AIM directory
- Fix memory detection on IBM LPARs and systems with more than one /memory
node (by andreast@)

The NetBSD Foundation has granted permission to remove clause 3 and 4 from
their software.

Obtained from: NetBSD

Forced commit to record that this file was repocopied from
src/sys/powerpc/powerpc and modified for its new location.

Instead of "OpenFirmware", "openfirmware", etc. use the official spelling
"Open Firmware" from IEEE 1275 and OpenFirmware.org (no pun intended).

Ok'ed by: tmm

Things run thru the C preprocessor must use C-style comments.

Bring in NetBSD code used in the PowerPC port.

Reviewed by: obrien, dfr
Obtained from: NetBSD