nnsp for m55

[poyupaulchen]

Three issues:

• This causes overflow:

  neuralSPOT/neuralspot/ns-nnsp/src/nn_speech.c

  Line 138 in e9af256

  int16x8_t val = (*pt_rawPCM * pt_inst->pt_params->pre_gain_q1) >> 1;

  
  Fixed:
  just comment it.
• Pointer error for specs:

  neuralSPOT/neuralspot/ns-nnsp/src/melSpecProc.c

  Line 21 in e9af256

  mac = interproduct_32x16(specs, (int16_t*) p_melBanks, len);

  
  Fixed:

mac = interproduct_32x16(specs+start_bin, (int16_t*) p_melBanks, len);

• Error for missing () before casting :

  neuralSPOT/neuralspot/ns-nnsp/src/spectrogram_module.c

  Line 281 in e9af256

  (int16_t*) ps->odataBuffer + ps->hop,

  
  Fixed:

(int16_t*) (ps->odataBuffer + ps->hop),