ivas crend function converted to fixed point.

Pytests:
573 failed, 381 skipped and 1 passed for original inputs, +10dB scaled and -10dB scaled inputs.

MLD:
Original: 2 cases > 5
9.195846 12.919653

+10dB: 10 cases > 5
5.072882 5.665263 5.665263 9.186245 10.756404 10.756404 16.599297 16.975319 27.041832 29.333475

-10dB: 1 case > 5
24.99962

MLD deviation issue to be debugged.