This is a minor revision to the previous patch as83.  It changes the name
of the various struct hd_driveid variables from 'drive' to 'id', per
Andries Brouwer's request.

 - Don't do DMA into the middle of a structure (info->drive).
 - Don't use I/O buffers for two different purposes simultaneously
 	(info->ATARegs, regs, us->iobuf).
 - Rename info->drive to info->id.