Contribute some example code which demonstrates how to initialise the

Contribute some example code which demonstrates how to initialise the
radar parameters for the AR5416 and later NICs.

These parameters have been tested on the following NICs:

* AR5416
* AR9160
* AR9220
* AR9280

And yes, these will return radar pulse parameters and (for AR9160 and later)
radar FFT information as PHY errors.

This is again not enough to do radar detection, it's just here to faciliate
development and validation of radar detection algorithms.

The (pulse, not FFT) decoding code for AR5212, AR5416 and later NICs exist
in the HAL.

This code is disabled for now as generating radar PHY errors can quickly
cause issues in busy environment.s  Some further debugging of the RX path
is needed.

Finally, these parameters are likely not useful for the AR5212 era NICs.
The madwifi-dfs branch should have suitable example parameters for the
11a era NICs.