scsi/NCR5380: merge sun3_scsi_vme.c into sun3_scsi.c

The sun3 drivers suffer from a whole bunch of duplicated code. Fix this
by following the g_NCR5380_mmio example. (Notionally, sun3_scsi relates to
sun3_scsi_vme in the same way that g_NCR5380 relates to g_NCR5380_mmio.)

Dead code is also removed: we now have working debug macros so
SUN3_SCSI_DEBUG is undesirable. Dead code within #ifdef OLD_DMA is also
dropped, consistent with sun3_scsi_vme.c.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: Sam Creasey <sammy@sammy.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>