Bugfix in CLPF RDO. Prevented selection of enable_fb_flag=0.

PSNR YCbCr:     -0.01%     -0.06%     -0.17%
   PSNRHVS:      0.01%
      SSIM:      0.03%
    MSSSIM:      0.00%
 CIEDE2000:     -0.05%

Change-Id: I1205c021bfc5cee6f80344fec92aabb529af9bd1

av1/encoder/encoder.c

@@ -3441,8 +3441,6 @@ static void loopfilter_frame(AV1_COMP *cpi, AV1_COMMON *cm) {
     av1_clpf_test_frame(frame, cpi->Source, cm, &strength_u, 0, AOM_PLANE_U);
     av1_clpf_test_frame(frame, cpi->Source, cm, &strength_v, 0, AOM_PLANE_V);
 
-    if (!fb_size_log2) fb_size_log2 = get_msb(MAX_FB_SIZE);
-
     if (strength_y) {
       // Apply the filter using the chosen strength
       cm->clpf_strength_y = strength_y - (strength_y == 4);