ivas sce, cpe modules converted to fixed point.

[x] There is a Macro IVAS_FLOAT_FIXED_TO_BE_REMOVED
defined in ivas_sce_dec_fx.c & ivas_cpe_dec_fx.c, it is
for computation happening in floating point. This macro
and code active under this is to be removed once the
intermediate conversions to float are not required.