ideapad: make sure we bind on the correct device

By reading from method _CFG to make sure we bind on the correct VPC2004 device.
Signed-off-by: Ike Panhc <ike.pan@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/ideapad_acpi.c

@@ -326,10 +326,13 @@ MODULE_DEVICE_TABLE(acpi, ideapad_device_ids);
 
 static int ideapad_acpi_add(struct acpi_device *adevice)
 {
-	int i;
+	int i, cfg;
 	int devs_present[5];
 	struct ideapad_private *priv;
 
+	if (read_method_int(adevice->handle, "_CFG", &cfg))
+		return -ENODEV;
+
 	for (i = IDEAPAD_DEV_CAMERA; i < IDEAPAD_DEV_KILLSW; i++) {
 		devs_present[i] = ideapad_dev_exists(i);
 		if (devs_present[i] < 0)