In the ISA case, we call ed_probe_WD80x3 before we call
ed_probe_rtl80x9. In the pci case we call ed_probe_rtl80x9 first. In
the PCI case we were using the correct nic_offset by accident because
softc is initialized to zero. In the isa case we were using the wrong
value by accident, since ed_probe_WD80x3 sets the offset value to
0x10. This lead to the identification routines failing. Fix this
problem by always initalizing the nic_offset and asic_offset before
making ed_{asic,nic}_{in,out}* calls.