Added new functions pci_device_map_range and pci_device_unmap_range to
handle mapping of PCI device BARs.  These new interfaces allow the
possiblity of MTRRs on platforms that support them.

These additional APIs necessitated changing some internal interfaces.  The
code for FreeBSD and Solaris has been updated but has not been compiled or
tested.

Old interfaces are marked deprecated and will eventually be removed.