Further correct bug in loopfilter initialization

The intent was to initialize the deltas for the
segment to the computed value, irrespective of mode
and reference frame if (mode_ref_delta_enabled == 0).

(In response to bug posted by Manjit Hota to codec-devel
and webm-discuss lists)

Change-Id: I10435cb63d0f88359bb4c14f22181878a1988e72

vp9/common/vp9_loopfilter.c

@@ -108,7 +108,7 @@ void vp9_loop_filter_frame_init(VP9_COMMON *const cm, int default_filt_lvl) {
     if (!lf->mode_ref_delta_enabled) {
       // we could get rid of this if we assume that deltas are set to
       // zero when not in use; encoder always uses deltas
-      vpx_memset(lfi->lvl[seg_id][0], lvl_seg, sizeof(lfi->lvl[seg_id][0]));
+      vpx_memset(lfi->lvl[seg_id], lvl_seg, sizeof(lfi->lvl[seg_id]));
       continue;
     }