staging: rtl8712: usb_intf.c: Fix for possible null pointer dereference

There is otherwise a risk of a possible null pointer dereference.

Was largely found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8712/usb_intf.c

@@ -595,7 +595,7 @@ static int r871xu_drv_init(struct usb_interface *pusb_intf,
 error:
 	usb_put_dev(udev);
 	usb_set_intfdata(pusb_intf, NULL);
-	if (padapter->dvobj_deinit != NULL)
+	if (padapter && padapter->dvobj_deinit != NULL)
 		padapter->dvobj_deinit(padapter);
 	if (pnetdev)
 		free_netdev(pnetdev);