qcacld-3.0: Return correct error code for big data stats

In SAP mode, the get sta info vendor command gets called for both
connected and disconnected state. If peer client is connected then
driver returns the SAP power save parameters to the userspace.
If peer client is disconnected then driver returns -EINVAL status.
Userspace cannot differentiate using this error code whether driver
is not able to handle the vendor command or peer client is
disconnected.

So, if peer client is disconnected then return -ENXIO error code
instead of -EINVAL.

CRs-Fixed: 3014906
Change-Id: I3ce5cd53e79c3bfaeed6571ea28b28ce2dfe26b3

core/hdd/src/wlan_hdd_station_info.c

@@ -2239,7 +2239,7 @@ static int hdd_get_station_remote_ex(struct hdd_context *hdd_ctx,
 	if (!stainfo) {
 		hdd_err_rl("Failed to get peer STA " QDF_MAC_ADDR_FMT,
 			   QDF_MAC_ADDR_REF(mac_addr.bytes));
-		return -EINVAL;
+		return -ENXIO;
 	}
 
 	is_associated = hdd_is_peer_associated(adapter, &mac_addr);