FD CNG buffer is not updated

In FD CNG decoder handle, the following buffers are defined:

hFdCngDec->hFdCngCom->olapBufferSynth[] 
hFdCngDec->hFdCngCom->olapBufferSynth_fx[]

The first one is Word16 and comes from the EVS, while the other one is Word32 and is intorduced in IVAS.

The issue is that the later buffer is never updated and used only at one switching place. I read the logic such that

• it is used wrongly in core_switching_pre_dec_ivas_fx()
• contains always only zeros from the initialization
• -> should be replaced by the first buffer