Remvoe EIGHTTAP_SHARP filter check for non-rd mode.

Using EIGHTTAP and EIGHTTAP_SMOOTH seem sufficient.
Hard to see any visual gain from allowing EIGHTTAP_SHARP, and it is
rarely selected.

PSNR/SSIM metrics go up by ~0.18/0.14%.

Change-Id: I96fa0d98f9321b913e3ebcd464d4ff3c63018791

vp9/encoder/vp9_pickmode.c

@@ -1322,7 +1322,7 @@ void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
       INTERP_FILTER best_filter = SWITCHABLE, filter;
       PRED_BUFFER *current_pred = this_mode_pred;
 
-      for (filter = EIGHTTAP; filter <= EIGHTTAP_SHARP; ++filter) {
+      for (filter = EIGHTTAP; filter <= EIGHTTAP_SMOOTH; ++filter) {
         int64_t cost;
         mbmi->interp_filter = filter;
         vp9_build_inter_predictors_sby(xd, mi_row, mi_col, bsize);