Fix transcribe_time not defined error when using partial audio.

Signed-off-by: Daniel Galvez <dgalvez@nvidia.com>

examples/asr/transcribe_speech.py

@@ -415,6 +415,8 @@ def autocast(dtype=None, enabled=True):
 
     with autocast(dtype=amp_dtype, enabled=cfg.amp):
         with torch.no_grad():
+            if cfg.calculate_rtfx:
+                start_time = time.time()
             if partial_audio:
                 transcriptions = transcribe_partial_audio(
                     asr_model=asr_model,
@@ -436,14 +438,12 @@ def autocast(dtype=None, enabled=True):
                 override_cfg.text_field = cfg.gt_text_attr_name
                 override_cfg.lang_field = cfg.gt_lang_attr_name
 
-                if cfg.calculate_rtfx:
-                    start_time = time.time()
                 transcriptions = asr_model.transcribe(
                     audio=filepaths,
                     override_config=override_cfg,
                 )
-                if cfg.calculate_rtfx:
-                    transcribe_time = time.time() - start_time
+            if cfg.calculate_rtfx:
+                transcribe_time = time.time() - start_time
 
     if cfg.dataset_manifest is not None:
         logging.info(f"Finished transcribing from manifest file: {cfg.dataset_manifest}")