[media] rc: ene_ir: fix potential double free in ene_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/ene_ir.c

@@ -1098,6 +1098,7 @@ exit_release_hw_io:
 	release_region(dev->hw_io, ENE_IO_SIZE);
 exit_unregister_device:
 	rc_unregister_device(rdev);
+	rdev = NULL;
 exit_free_dev_rdev:
 	rc_free_device(rdev);
 	kfree(dev);