scsi: initio: Remove unused variable 'prev'

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

 drivers/scsi/initio.c: In function ‘initio_find_busy_scb’:
 drivers/scsi/initio.c:869:30: warning: variable ‘prev’ set but not used [-Wunused-but-set-variable]

Link: https://lore.kernel.org/r/20210312094738.2207817-24-lee.jones@linaro.org
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Bas Vermeulen <bvermeul@blackstar.xs4all.nl>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Brian Macy <bmacy@sunshinecomputing.com>
Cc: linux-scsi@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/initio.c

@@ -866,17 +866,16 @@ static void initio_unlink_busy_scb(struct initio_host * host, struct scsi_ctrl_b
 
 struct scsi_ctrl_blk *initio_find_busy_scb(struct initio_host * host, u16 tarlun)
 {
-	struct scsi_ctrl_blk *tmp, *prev;
+	struct scsi_ctrl_blk *tmp;
 	u16 scbp_tarlun;
 
 
-	prev = tmp = host->first_busy;
+	tmp = host->first_busy;
 	while (tmp != NULL) {
 		scbp_tarlun = (tmp->lun << 8) | (tmp->target);
 		if (scbp_tarlun == tarlun) {	/* Unlink this SCB              */
 			break;
 		}
-		prev = tmp;
 		tmp = tmp->next;
 	}
 #if DEBUG_QUEUE