[media] rc: nuvoton-cir: fix potential double free in nvt_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: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/rc/nuvoton-cir.c

@@ -1107,6 +1107,7 @@ static int nvt_probe(struct pnp_dev *pdev, const struct pnp_device_id *dev_id)
 	release_region(nvt->cir_addr, CIR_IOREG_LENGTH);
 exit_unregister_device:
 	rc_unregister_device(rdev);
+	rdev = NULL;
 exit_free_dev_rdev:
 	rc_free_device(rdev);
 	kfree(nvt);