Duplication of function ivas_get_nchan_buffers_dec in BASOP

Basic info

• Fixed point:
  • Decoder (fixed): main

Bug description

There is a duplication of ivas_get_nchan_buffers_dec to ivas_get_nchan_buffers_dec_ivas_fx. However, this is not a direct duplication as the contents differ and both sides seem to have some peculiarities or wrong conversions. I think these should be reduced to a single function as soon as possible due to possibility of missing changes on one of the paths.

My rough feeling is that the first of those functions is closer to correct state.