player/audio: remove misleading comment about delay

This came up in mpv-player#13571. playing_audio_pts does not include mpctx->delay
contray to what that implies. The function is meant to only offset the
written audio pts by whatever the internal AO buffer may be.
mpctx->delay is a combination from both the audio and video code, so it
should not be used here. What is wanted is purely the audio pts.
b74c09e, a very controversial commit to
say the least, was what introduced this comment, so removing is probably
OK.

player/audio.c

@@ -845,7 +845,7 @@ void audio_start_ao(struct MPContext *mpctx)
     double pts = MP_NOPTS_VALUE;
     if (!get_sync_pts(mpctx, &pts))
         return;
-    double apts = playing_audio_pts(mpctx); // (basically including mpctx->delay)
+    double apts = playing_audio_pts(mpctx);
     if (pts != MP_NOPTS_VALUE && apts != MP_NOPTS_VALUE && pts < apts &&
         mpctx->video_status != STATUS_EOF)
     {