qcacmn: Log failures to prevent PCIe power collapse

Currently there is no indication when calls into pld_wlan_pm_control
fail. Add an error log in such situations to improve debugging.

Change-Id: Ic061a1735878930a5ab55711da58f8bad1a6a8a6
CRs-Fixed: 2119173

hif/src/pcie/if_pci.c

@@ -2718,10 +2718,15 @@ static void hif_runtime_prevent_linkdown(struct hif_softc *scn, bool flag)
  */
 void hif_pci_prevent_linkdown(struct hif_softc *scn, bool flag)
 {
-	HIF_DBG("wlan: %s pcie power collapse",
-			(flag ? "disable" : "enable"));
+	int errno;
+
+	HIF_DBG("wlan: %s pcie power collapse", flag ? "disable" : "enable");
 	hif_runtime_prevent_linkdown(scn, flag);
-	pld_wlan_pm_control(scn->qdf_dev->dev, flag);
+
+	errno = pld_wlan_pm_control(scn->qdf_dev->dev, flag);
+	if (errno)
+		HIF_ERROR("%s: Failed pld_wlan_pm_control; errno %d",
+			  __func__, errno);
 }
 #else
 void hif_pci_prevent_linkdown(struct hif_softc *scn, bool flag)