Functions in ivas_masa_dec converted to fixed point.

[x] Functions in ivas_masa_dec converted to fixed point.
[x] Some changes in calling and sub-functions included.

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

MLD:
Original: 1 case > 5
9.195846

+10dB: 9 cases > 5
5.072882 5.665263 5.665263 9.186245 10.756404 10.756404 16.599295 16.975319 29.333475