Next round of PCI subsystem updates:

Next round of PCI subsystem updates:

 - Break out the /dev/pci driver into a separate file.
 - Kill the COMPAT_OLDPCI support.
 - Make the EISA bridge attach a bit more like the old code; explicitly
   check for the existence of eisa0/isa0 and only attach if they don't
   already exist.  Only make one bus_generic_attach() pass over the
   bridge, once both busses are attached.  Note that the stupid Intel
   bridge's class is entirely unpredictable.
 - Add prototypes and re-layout the core PCI modules in line with
   current coding standards (not a major whitespace change, just moving
   the module data to the top of the file).
 - Remove redundant type-2 bridge support from the core PCI code; the
   PCI-CardBus code does this itself internally.  Remove the now
   entirely redundant header-class-specific support, as well as the
   secondary and subordinate bus number fields.  These are bridge
   attributes now.
 - Add support for PCI Extended Capabilities.
 - Add support for PCI Power Management.  The interface currently
   allows a driver to query and set the power state of a device.
 - Add helper functions to allow drivers to enable/disable busmastering
   and the decoding of I/O and memory ranges.
 - Use PCI_SLOTMAX and PCI_FUNCMAX rather than magic numbers in some
   places.
 - Make the PCI-PCI bridge code a little more paranoid about valid
   I/O and memory decodes.
 - Add some more PCI register definitions for the command and status
   registers.  Correct another bogus definition for type-1 bridges.