[media] Prevent null pointer derefernce of pdev

Make sure pdev is not dereferenced when it is null
Signed-off-by: Huzaifa Sidhpurwala <huzaifas@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/pwc/pwc-if.c

@@ -1850,7 +1850,6 @@ static void usb_pwc_disconnect(struct usb_interface *intf)
 	} else {
 		/* Device is closed, so we can safely unregister it */
 		PWC_DEBUG_PROBE("Unregistering video device in disconnect().\n");
-		pwc_cleanup(pdev);
 
 disconnect_out:
 		/* search device_hint[] table if we occupy a slot, by any chance */
@@ -1860,6 +1859,7 @@ static void usb_pwc_disconnect(struct usb_interface *intf)
 	}
 
 	mutex_unlock(&pdev->modlock);
+	pwc_cleanup(pdev);
 }