vad : remove unused struct

Author: danbev

src/whisper.cpp

@@ -4458,11 +4458,6 @@ struct whisper_vad_params whisper_vad_default_params(void) {
     return result;
 }
 
-struct whisper_vad_result {
-    float probability;  // Speech probability (0-1)
-};
-
-
 static bool weight_buft_supported(const whisper_vad_hparams & hparams, ggml_tensor * w, ggml_op op, ggml_backend_buffer_type_t buft, ggml_backend_dev_t dev) {
     bool op_supported = true;
     return op_supported;