plugins.afreeca: Fix HLS stream.
plugins.afreeca: Fix HLS stream.

Resolves #982.

sbstp/streamlink,beardypig/streamlink,streamlink/streamlink,back-to/streamlink,mmetak/streamlink,sbstp/streamlink,streamlink/streamlink,melmorabity/streamlink,bastimeyer/streamlink,back-to/streamlink,gravyboat/streamlink,fishscene/streamlink,javiercantero/streamlink,javiercantero/streamlink,ethanhlc/streamlink,gravyboat/streamlink,chhe/streamlink,chhe/streamlink,fishscene/streamlink,ethanhlc/streamlink,mmetak/streamlink,wlerin/streamlink,beardypig/streamlink,bastimeyer/streamlink,wlerin/streamlink,melmorabity/streamlink