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:
i4b_isic_isa.c -> isic_isa.c
i4b_avm_a1.c -> isic_isa_avm_a1.c
i4b_daic_isa.c -> daic_isa.c
i4b_itk_ix1.c -> isic_isa_itk_ix1.c
i4b_tel_s08.c -> isic_isa_tel_s08.c
i4b_tel_s016.c -> isic_isa_tel_s016.c
i4b_tel_s0163.c -> isic_isa_tel_s0163.c
i4b_usr_sti.c -> isic_isa_usr_sti.c
