Bugfix in TPCFastTransform with reduced metadata

[sgorbuno]

Hi David, Ruben.

@davidrohr, @shahor02

This PR fixes the commit bd7be4f9a69b37b50ee0fcd3c94b58a6b346d4cb
"TPCFastTransform: reduce the metadata: the same spline setup for all the sectors"

The TPCFastSpaceChargeCorrection and the TPCFastTransformPOD now show the same results everywhere on the CPU.
I didn't test it on the GPU, but it must work. David, please check.

There is a little difference (of the order of 1.e-6 at max) in getCorrectionYZatRealYZ(..) between the POD and the standard version of the SC correction.

I assume the difference is due to differences in the code optimization.

This difference was not there before. It appears right after the commit b90942c92ed3bc599e157472db21585069483325
"TPCFastTransform: remove row-wise max correction values"

It disappears again when I disable the check for the large values in getCorrectionYZatRealYZ() by commenting out the corresponding lines:

https://github.com/sgorbuno/AliceO2/blob/PR21.04/GPU/TPCFastTransformation/TPCFastSpaceChargeCorrection.h#L500
https://github.com/sgorbuno/AliceO2/blob/PR21.04/GPU/TPCFastTransformation/TPCFastTransformPOD.h#L362

Interesting: in my test, the check for large values is never triggered. But just the presence of this check in the code changes the calculations, apparently.

[davidrohr]

fix works, thx a lot.
Well, by default we compile with -ffast-math, so changes in the code can change the results slightly