hud: use s->data_[wh] instead of hardcoded DATA_[WH]
hud: use s->data_[wh] instead of hardcoded DATA_[WH]

The width/height of the buffer will be dynamic in the future.

gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl