separate kernel module. Update pci bus attach routine to load the
module (if available) when we're about to start scanning the bus, and
unload the module after the scan is finished.
On architectures which support loading of modules by the boot loader,
the 'pciverbose' module can be loaded and executed without needing to
rebuild the kernel. On all architectures, using 'options PCIVERBOSE'
in the kernel configuration file will create a 'builtin' module which
is functionally equivalent to previous behavior.
XXX Although not nearly as large as the vendor and product tables,
XXX the PCI class and subclass tables might also be offloaded into
XXX the module at a future time.
XXX Cardbus (and possibly other) drivers should also be modified to
XXX load the module before scanning/attaching devices.