[SCSI] qla4xxx: Clear interrupt while unloading driver.

while processing the stop firmware mailbox command on driver unload,
a interrupt is processed which causes kernel panic as the response
queue is not valid.

Fix is to clear the interrupt in free_adapter call just after
disabling the interrupts.
Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/qla4xxx/ql4_os.c

@@ -3487,6 +3487,15 @@ static void qla4xxx_free_adapter(struct scsi_qla_host *ha)
 		ha->isp_ops->disable_intrs(ha);
 	}
 
+	if (is_qla40XX(ha)) {
+		writel(set_rmask(CSR_SCSI_PROCESSOR_INTR),
+		       &ha->reg->ctrl_status);
+		readl(&ha->reg->ctrl_status);
+	} else if (is_qla8022(ha)) {
+		writel(0, &ha->qla4_8xxx_reg->host_int);
+		readl(&ha->qla4_8xxx_reg->host_int);
+	}
+
 	/* Remove timer thread, if present */
 	if (ha->timer_active)
 		qla4xxx_stop_timer(ha);