scsi: gdth: remove ISA and EISA support

The non-PCI code has bitrotted for quite a while and will just oops
on load because it passes a NULL pointer to the PCI DMA routines.

Lets kill it for good - if someone really wants to use one of these
cards I'll help mentoring them to write a proper driver glue.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>