Remove outdated comments from encoder.c

Change-Id: I6af9db41b24a73c5af4494693fec5a39934f4863
diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index 3221d84..2e12dbd 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -2530,9 +2530,6 @@
   cm->cur_frame->buf.render_width = cm->render_width;
   cm->cur_frame->buf.render_height = cm->render_height;
 
-  // TODO(zoeliu): For non-ref frames, loop filtering may need to be turned
-  // off.
-
   // Pick the loop filter level for the frame.
   if (!cm->features.allow_intrabc) {
     loopfilter_frame(cpi, cm);