Modify pciconf(8) so that it will print out PCI devices that have no driver

Modify pciconf(8) so that it will print out PCI devices that have no driver
configured in the kernel.  It gives them a device name of "none" and
monotonically incrementing unit numbers.  (starting at 0)  Before, pciconf
would just skip over unconfigured devices.  (unconfigured devices can be
detected because they have a null string for a device name)

Update the man page to reflect the new pciconf output.  Unfortunately, this
causes the sample 'pciconf -l' output lines to wrap, but I'm not sure what
to do about that really.

If anyone presents a reasonable case for printing out something other than
"none1" for unconfigured devices, I'm willing to listen.