configuration information from a DPT card at a given port.
This is needed by the ISA bus front end (still to come) and the EISA
bus front end (which hasn't ever worked).
- Blow away dpt_eisa.h as the information it contains does not justify
an additional file.
- Convert dpt_eisa.c to use the onboard config instead of trying to
read the EISA configuration registers.