remove all (legacy) "i4b_" prefixes outside of sys/netisdn.
Prefix all card specific driver support files with the basename
of the driver bus attachement file.
Renamed here:
pci_isic.h -> isic_pci.h
pci_isic.c -> isic_pci.c
i4b_avm_fritz_pci.c -> isic_pci_avm_fritz_pci.c
i4b_elsa_qs1p.c -> isic_pci_elsa_qs1p.c