[turbo] Improve description extraction

`og:description` is empty for some videos.

youtube_dl/extractor/turbo.py

@@ -23,7 +23,7 @@ class TurboIE(InfoExtractor):
             'ext': 'mp4',
             'duration': 3715,
             'title': 'Turbo du 07/09/2014 : Renault Twingo 3, Bentley Continental GT Speed, CES, Guide Achat Dacia... ',
-            'description': 'Retrouvez dans cette rubrique toutes les vidéos de l\'Turbo du 07/09/2014 : Renault Twingo 3, Bentley Continental GT Speed, CES, Guide Achat Dacia... ',
+            'description': 'Turbo du 07/09/2014 : Renault Twingo 3, Bentley Continental GT Speed, CES, Guide Achat Dacia...',
             'thumbnail': 're:^https?://.*\.jpg$',
         }
     }
@@ -42,7 +42,7 @@ class TurboIE(InfoExtractor):
         title = xpath_text(item, './title', 'title')
         duration = int_or_none(xpath_text(item, './durate', 'duration'))
         thumbnail = xpath_text(item, './visuel_clip', 'thumbnail')
-        description = self._og_search_description(webpage)
+        description = self._html_search_meta('description', webpage)
 
         formats = []
         get_quality = qualities(['3g', 'sd', 'hq'])