lpd functions converted to fixed

[x] Contains float to fix and vice versa conversions for subfunctions of mode_switch_decoder_LPD
[x] Contains float_to_fx and vice versa conversions for subfunctions of open_decoder_LPD
[x] Contains cosmetic changes(comparsion, basop , type etc.) for dec_prm_tcx and stereo_tcx_dec_mode_switch_reconf
[x] Added fixed table for igf_whitening_TH_flt