i4bq931, i4b, isic, iwic, ifpi, ifpi2, ifpnp, ihfc, and itjc are
no longer count devices. Also remove a few other instances of N<DEVICE>
being used to control compilation of whole files.
Reviewed by: hm
Add a CAPI (hardware independent) driver i4bcapi(4) and hardware driver
iavc (4) to support active CAPI-based BRI and PRI cards (currently AVM
B1 and T1 cards) to isdn4bsd.