scsi: hisi_sas: remove set but not used variable 'irq_value'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/scsi/hisi_sas/hisi_sas_v1_hw.c: In function cq_interrupt_v1_hw:
drivers/scsi/hisi_sas/hisi_sas_v1_hw.c:1542:6: warning: variable irq_value set but not used [-Wunused-but-set-variable]
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Acked-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hisi_sas/hisi_sas_v1_hw.c

@@ -1497,11 +1497,9 @@ static irqreturn_t cq_interrupt_v1_hw(int irq, void *p)
 	struct hisi_sas_complete_v1_hdr *complete_queue =
 			(struct hisi_sas_complete_v1_hdr *)
 			hisi_hba->complete_hdr[queue];
-	u32 irq_value, rd_point = cq->rd_point, wr_point;
+	u32 rd_point = cq->rd_point, wr_point;
 
 	spin_lock(&hisi_hba->lock);
-	irq_value = hisi_sas_read32(hisi_hba, OQ_INT_SRC);
-
 	hisi_sas_write32(hisi_hba, OQ_INT_SRC, 1 << queue);
 	wr_point = hisi_sas_read32(hisi_hba,
 			COMPL_Q_0_WR_PTR + (0x14 * queue));