Bug#166675: discover: format string should support device id

[Petter Reinholdtsen <pere@hungry.com>]

I've tried to make a script to automatically compare the output from
lspci, lspci -n and discover, to detect which devices are missing in
the discover database.  This has proven very hard when there is no
common "key" to use when comparing devices between the output of the
two tools.

Being able to print the bus ID (PCI ID) with discover, would make this
a lot easier.  In fact, I belive it is impossible to do this reliably
without such feature.

I suggest implementing this using %i for device ID, and %I for vendor
ID.  This way one could ask for '%I:%i', and compare this value
against the output from lspci -n.