[ath_hal] Add setting positioning bit and clear sounding-disable bit.

• If fast_ts is set then the TX timestamp is the fast timestamp, not normal TSF.
• If the TX descriptor has the position bit set then request locationing and clear sounding-disable. This way we (a) get the response with the TX timestamp from the location side of things, and (b) we get a CSI dump of the response ACK, which we will eventually use in the locationing path.