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