aic7xxx_old: removed unused 'req' variable

After the patch "block: remove spurious uses of REQ_HARDBARRIER",
we no longer use 'req' in aic7xxx_buildscb(). Kill it.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

drivers/scsi/aic7xxx_old.c

@@ -10119,7 +10119,6 @@ static void aic7xxx_buildscb(struct aic7xxx_host *p, struct scsi_cmnd *cmd,
   struct aic_dev_data *aic_dev = cmd->device->hostdata;
   struct scsi_device *sdptr = cmd->device;
   unsigned char tindex = TARGET_INDEX(cmd);
-  struct request *req = cmd->request;
   int use_sg;
 
   mask = (0x01 << tindex);