AP_HAL: Delete commented-out processes

[muramura]

Only the contributor who commented out the process knows the reason for leaving the process commented out when it is no longer needed.
Therefore, delete it as an unnecessary process.

[peterbarker]

Only the contributor who commented out the process knows the reason for leaving the process commented out when it is no longer needed. Therefore, delete it as an unnecessary process.

I'm the "contributor" here, and I think I remember why. This code is duplicated between sitl-on-hardware and normal SITL, and I didn't want to fight with frsky for real hardware.