SweepFormula: tpfit operation is not aware of different AD/DA sample rates

[MichaelHuth]

tp fitting with SweepFormula uses the sample rate in the fitting process.

Before support for Sutter hardware was introduced DA and AD sample rates were the same.

Now with Sutter hardware these can be different and this need to be supported properly. The tp fitting code in SF needs to be reviewed and adapted to use the correct sample rate for the fitting.