Clean up the DMA interface too much unneeded stuff crept in with
the busdma code back when.
Modify the ATA_IN* / ATA_OUT* macros so that resource and offset
are gotten from a table. That allows for new chipsets that doesn't
nessesarily have things ordered the good old way. This also removes
the need for the wierd PC98 resource functions.
Tested on: i386, PC98, Alpha, Sparc64