scsi: qla2xxx: Use shadow register for ISP27XX

For ISP27XX, use shadow register to read FW provided REQQ's consumer
index. The shadow register is dma'ed by firmware.
Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_iocb.c

@@ -2158,7 +2158,9 @@ __qla2x00_alloc_iocbs(struct qla_qpair *qpair, srb_t *sp)
 skip_cmd_array:
 	/* Check for room on request queue. */
 	if (req->cnt < req_cnt + 2) {
-		if (ha->mqenable || IS_QLA83XX(ha) || IS_QLA27XX(ha))
+		if (qpair->use_shadow_reg)
+			cnt = *req->out_ptr;
+		else if (ha->mqenable || IS_QLA83XX(ha) || IS_QLA27XX(ha))
 			cnt = RD_REG_DWORD(&reg->isp25mq.req_q_out);
 		else if (IS_P3P_TYPE(ha))
 			cnt = RD_REG_DWORD(&reg->isp82.req_q_out);