Add POWER7+ and POWER8 to the CPU ID table.

Approved by:	re (kib)
CDs are not partitioned, so this is not correct syntax for loading from
ISO 9660. Omit the partition ID.

Approved by:	re (kib)
MFC after:	2 weeks
Only attach if properties we need (address, in particular) are present.
This is the correct version of r255420.

Approved by:	re (kib)
Merge in support for PAPR-compliant (Power Architecture Platform
Requirements) systems from the projects/pseries branch. This in principle
includes all IBM POWER hardware released in the last 15 years with the
exception of POWER3-based systems when run in 64-bit mode. The main
development target, however, has been the PAPR logical partition support
that is the default target in KVM on POWER and QEMU -- mileage may vary
on actual hardware at present. Much of the heavy lifting here was done
by Andreas Tobler.

Approved by:	re (kib)
Hide TSC-deadline APIC timer support from guests. This mode
isn't yet implemented in bhyve's APIC emulation.

Reviewed by:	neel
Approved by:	re@ (blanket)