scsi: pm80xx: Make phy enable completion as NULL

After the completing the mpi_phy_start_resp, make phy enable completion as
NULL.

Link: https://lore.kernel.org/r/20191114100910.6153-3-deepak.ukey@microchip.com
Acked-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: peter chang <dpf@google.com>
Signed-off-by: Deepak Ukey <deepak.ukey@microchip.com>
Signed-off-by: Viswas G <Viswas.G@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/pm8001/pm80xx_hwi.c

@@ -3132,8 +3132,10 @@ static int mpi_phy_start_resp(struct pm8001_hba_info *pm8001_ha, void *piomb)
 	if (status == 0) {
 		phy->phy_state = PHY_LINK_DOWN;
 		if (pm8001_ha->flags == PM8001F_RUN_TIME &&
-				phy->enable_completion != NULL)
+				phy->enable_completion != NULL) {
 			complete(phy->enable_completion);
+			phy->enable_completion = NULL;
+		}
 	}
 	return 0;