Disable sf 'disable_smooth_intra' for speed>=2

This patch disables the speed feature 'disable_smooth_intra' for
speed = 2, 3 and 4.

Encoder performance results averaged over all resolutions are as
follows:

     Encoder Instruction           BD-Rate Loss(%)
cpu   Count Reduction(%)  avg.psnr     ssim     vmaf    vmaf_neg
 2       -1.69            -0.1946    -0.2224  -0.2871   -0.2294
 3       -0.75            -0.1622    -0.1741  -0.1870   -0.1921
 4       -1.25            -0.1551    -0.2080  -0.1078   -0.1121

STATS_CHANGED for speed = 2, 3 and 4

Change-Id: Ie5525a644f53ab1e5af54541230ed444a353b85e

av1/encoder/speed_features.c

diff --git a/av1/encoder/speed_features.c b/av1/encoder/speed_features.c
index e2b04ca..f5ca507 100644
--- a/av1/encoder/speed_features.c
+++ b/av1/encoder/speed_features.c
@@ -1238,8 +1238,6 @@
 
     sf->interp_sf.adaptive_interp_filter_search = 1;
 
-    sf->intra_sf.disable_smooth_intra =
-        !frame_is_intra_only(&cpi->common) || (cpi->rc.frames_to_key > 1);
     sf->intra_sf.intra_pruning_with_hog = 2;
     sf->intra_sf.skip_intra_in_interframe = is_inter_frame ? 2 : 1;
     sf->intra_sf.skip_filter_intra_in_inter_frames = 1;
@@ -1419,6 +1417,7 @@
     sf->interp_sf.skip_interp_filter_search = boosted ? 0 : 1;
 
     sf->intra_sf.chroma_intra_pruning_with_hog = 3;
+    sf->intra_sf.disable_smooth_intra = 1;
 
     // TODO(any): Extend multi-winner mode processing support for inter frames
     sf->winner_mode_sf.multi_winner_mode_type =