Move code to set various MSRs on AMD cpus out of printcpuinfo() and
into initalizecpu() instead.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271405 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Add support for calling pcibios routines from the
bootloader. Implement the following routines:
	pcibios-device-count	count the number of instances of a devid
	pcibios-read-config	read pci config space
	pcibios-write-config	write pci config space
	pcibios-find-devclass	find the nth device with a given devclass
	pcibios-find-device	find the nth device with a given devid
	pcibios-locator		convert bus device function ti pcibios locator
These commands are thin wrappers over their PCI BIOS 2.1 counterparts. More
informaiton, such as it is, can be found in the standard.

Export a nunmber of pcibios.X variables into the environment to report
what the PCI IDENTIFY command returned.

Also implmenet a new command line primitive (pci-device-count), but don't
include it by default just yet, since it depends on the recently added
words and any errors here can render a system unbootable.

This is intended to allow the boot loader to do special things based
on the hardware it finds. This could be have special settings that are
optimized for the specific cards, or even loading special drivers. It
goes without saying that writing to pci config space should not be
done without a just cause and a sound mind.

Sponsored by:	Netflix


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271406 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f