Fix incorrect format codes

Corrects the descriptions for the DASH video format codes 264 and 138
(1440p and 2160p, respectively).

youtube_dl/extractor/youtube.py

@@ -199,9 +199,9 @@ class YoutubeIE(YoutubeBaseInfoExtractor, SubtitlesInfoExtractor):
         '135': {'ext': 'mp4', 'height': 480, 'resolution': '480p', 'format_note': 'DASH video', 'preference': -40},
         '136': {'ext': 'mp4', 'height': 720, 'resolution': '720p', 'format_note': 'DASH video', 'preference': -40},
         '137': {'ext': 'mp4', 'height': 1080, 'resolution': '1080p', 'format_note': 'DASH video', 'preference': -40},
-        '138': {'ext': 'mp4', 'height': 1081, 'resolution': '>1080p', 'format_note': 'DASH video', 'preference': -40},
+        '138': {'ext': 'mp4', 'height': 2160, 'resolution': '2160p', 'format_note': 'DASH video', 'preference': -40},
         '160': {'ext': 'mp4', 'height': 192, 'resolution': '192p', 'format_note': 'DASH video', 'preference': -40},
-        '264': {'ext': 'mp4', 'height': 1080, 'resolution': '1080p', 'format_note': 'DASH video', 'preference': -40},
+        '264': {'ext': 'mp4', 'height': 1440, 'resolution': '1440p', 'format_note': 'DASH video', 'preference': -40},
 
         # Dash mp4 audio
         '139': {'ext': 'm4a', 'format_note': 'DASH audio', 'vcodec': 'none', 'abr': 48, 'preference': -50},