[SCSI] dc395x: "fix" virt_addr calculation on AUTO_REQSENSE

The patch below "fixes" calculation of the virt_addr for the AUTO_REQSENSE
case. I put "fixes" in quotes because the real fix would be to completely
remove it, but that's beyond the scope of this patch.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>