Move subpel_force_stop features to speed 3

Moved the speed feature that reduces sub-pel search precision to
1/4 pel in TPL and simple motion search to speed 3. The speed/
quality tradeoff is fine.

Borg test result at speed 3:
       avg_psnr:  ovr_psnr:  ssim:   avg speed change:
hdres:  0.029	   0.018    -0.085      1.5%
midres: 0.059	   0.051    -0.026      1.4%
lowres: 0.036	   0.023    -0.100      0.8%

STATS_CHANGED

Change-Id: I82d832b2fac71ee96d3eb44b832c98580179e725
diff --git a/av1/encoder/speed_features.c b/av1/encoder/speed_features.c
index e03faec..d537477 100644
--- a/av1/encoder/speed_features.c
+++ b/av1/encoder/speed_features.c
@@ -446,6 +446,7 @@
     // See aomedia:1778.
     // sf->mv_sf.adaptive_motion_search = 1;
     sf->mv_sf.full_pixel_search_level = 1;
+    sf->mv_sf.simple_motion_subpel_force_stop = QUARTER_PEL;
     sf->mv_sf.subpel_search_method = SUBPEL_TREE_PRUNED;
     sf->mv_sf.use_accurate_subpel_search = USE_2_TAPS;
     sf->mv_sf.search_method = DIAMOND;
@@ -475,6 +476,7 @@
     sf->tpl_sf.skip_alike_starting_mv = 2;
     sf->tpl_sf.prune_intra_modes = 1;
     sf->tpl_sf.reduce_first_step_size = 6;
+    sf->tpl_sf.subpel_force_stop = QUARTER_PEL;
 
     sf->tx_sf.adaptive_txb_search_level = boosted ? 2 : 3;
     sf->tx_sf.tx_type_search.use_skip_flag_prediction =
@@ -591,11 +593,8 @@
     sf->lpf_sf.lpf_pick = LPF_PICK_FROM_FULL_IMAGE_NON_DUAL;
     sf->lpf_sf.disable_lr_filter = 1;
 
-    sf->mv_sf.simple_motion_subpel_force_stop = QUARTER_PEL;
     sf->mv_sf.prune_mesh_search = 1;
     sf->mv_sf.reduce_search_range = 1;
-
-    sf->tpl_sf.subpel_force_stop = QUARTER_PEL;
   }
 
   if (speed >= 6) {