media: dvbdev: remove double-unlock

As warned by smatch:
	drivers/media/dvb-core/dvbdev.c: drivers/media/dvb-core/dvbdev.c:529 dvb_register_device() error: double unlock 'sem:&minor_rwsem'
Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/dvb-core/dvbdev.c

@@ -526,7 +526,6 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
 		dvb_media_device_free(dvbdev);
 		kfree(dvbdevfops);
 		kfree(dvbdev);
-		up_write(&minor_rwsem);
 		mutex_unlock(&dvbdev_register_lock);
 		return ret;
 	}