[SCSI] m68k: new mac_esp scsi driver

Replace the mac_esp driver with a new one based on the esp_scsi core.

For esp_scsi: add support for sync transfers for the PIO mode, add a new
esp_driver_ops method to get the maximum dma transfer size (like the old
NCR53C9x driver), and some cleanups.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>