[media] rc: winbond-cir: fix potential double free in wbcir_probe()

Since rc_unregister_device() frees its argument, the subsequently
call to rc_free_device() on the same variable will cause a double
free bug. Fix by set argument to NULL, thus when fall through to
rc_free_device(), nothing will be done there.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/rc/winbond-cir.c

@@ -1151,6 +1151,7 @@ wbcir_probe(struct pnp_dev *device, const struct pnp_device_id *dev_id)
 	release_region(data->wbase, WAKEUP_IOMEM_LEN);
 exit_unregister_device:
 	rc_unregister_device(data->dev);
+	data->dev = NULL;
 exit_free_rc:
 	rc_free_device(data->dev);
 exit_unregister_led: