scsi: aic7xxx: Remove unused variable 'ahd'

Hasn't been used since 2005.

Fixes the following W=1 kernel build warning(s):

 drivers/scsi/aic7xxx/aic79xx_osm.c: In function ‘ahd_linux_slave_configure’:
 drivers/scsi/aic7xxx/aic79xx_osm.c:703:20: warning: variable ‘ahd’ set but not used [-Wunused-but-set-variable]

Link: https://lore.kernel.org/r/20200713080001.128044-22-lee.jones@linaro.org
Cc: Hannes Reinecke <hare@suse.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aic7xxx/aic79xx_osm.c

@@ -700,9 +700,6 @@ ahd_linux_slave_alloc(struct scsi_device *sdev)
 static int
 ahd_linux_slave_configure(struct scsi_device *sdev)
 {
-	struct	ahd_softc *ahd;
-
-	ahd = *((struct ahd_softc **)sdev->host->hostdata);
 	if (bootverbose)
 		sdev_printk(KERN_INFO, sdev, "Slave Configure\n");