Some conditions in core_switching_post_dec_fx() were wrong

Basic info

• Float reference:
  • Encoder (float):
  • Decoder (float): 4cb9c9482a79147b7c06f8fe1fc55639cddb75b8
• Fixed point:
  • Encoder (fixed):
  • Decoder (fixed): 86b6cd0a

Bug description

Some conditions in fixed don't seem to reflect the floating point conditions

Ways to reproduce

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-xxxx

running self_test we get 
10 conditions are not BE with their reference vectors
 maximum difference of +/-632 encountered in condition:
  OSBA FOA 4ISM at br sw 13.2 to 512 kbps, 48kHz in, 16kHz out, BINAURAL out (Model from file), FER at 5%, bandwidth switching
 The following conditions are not BE:
  - 4 ISM w and wo md br switching 24.4 kbps to 256 kbps, 48 kHz in, 48 kHz out, DTX on, BINAURAL_ROOM_IR out (Model from file) (+/-2)
  - 1 ISM at 24.4 kbps, 16 kHz in, 16 kHz out, BINAURAL out (Model from file), LR-toggle  (+/-117)
  - OMASA 1Dir2TC 3ISM at 160 kbps, 16kHz in, 32kHz out, HOA3 out (+/-9)
  - 4 ISM with and without metadata bitrate switching from 24.4 kbps to 256 kbps, 48 kHz in, 48 kHz out, DTX on, HOA3 out (+/-4)
  - Multi-channel 5_1 at 24.4 kbps, 48kHz in, 48kHz out, BINAURAL out, bandwidth switching (+/-40)
  - OMASA vdir1TC 3ISM at 96 kbps, 48kHz in, 48kHz out, MONO out (+/-1)
  - OSBA FOA 4ISM at br sw 13.2 to 512 kbps, 48kHz in, 16kHz out, BINAURAL out (Model from file), FER at 5%, bandwidth switching (+/-632)
  - OMASA vdir2TC 1ISM at 128 kbps, 48kHz in, 48kHz out, EXT out, bandwidth switching (+/-599)
  - 4 ISM with and without extended metadata bitrate switching from 24.4 kbps to 256 kbps, 48 kHz in, 48 kHz out, DTX on, EXT out (+/-512)
  - 4 ISM with metadata at 128 kbps, 48 kHz in, 48 kHz out, EXT out, bandwidth switching (+/-266)