Make sf40c rotation rate configurable

#### Issue details
I observed a wobble when the rotation rate is at high speed. It is currently hard coded to 4.5 revolutions per second. I hard coded it to 1 rotation per sec and the wobble went away. It would be nice to make this configurable.

#### Version
3.5

#### Platform
[ ] All
[ ] AntennaTracker
[ X ] Copter
[ ] Plane
[ ] Rover
[ ] Submarine

#### Airframe type
hex

#### Hardware type
PX4FMU

Start by searching the Copter source for the sf40c implementation and its hard-coded 4.5 revolutions-per-second value. Trace how the rotation rate is applied and identify the existing configuration mechanism; the issue names no file or test, so completion should include a maintainer-confirmed way to configure and verify the rate on the Copter hex/PX4FMU setup.

Written by the indexing model from the issue text.