Compute prediction filter type cost only when needed

Skip redundant prediction filter type cost in filter search loop,
if the rate value will be reset in Hadamard transform based rate
distortion estimate.

Change-Id: Ie5221f4bc8da9461c449df367251aeeac52c6e5d

vp9/encoder/vp9_pickmode.c

@@ -1336,9 +1336,6 @@ void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
         model_rd_for_sb_y(cpi, bsize, x, xd, &this_rdc.rate, &this_rdc.dist,
                           &var_y, &sse_y);
       }
-      this_rdc.rate +=
-          cm->interp_filter == SWITCHABLE ?
-              vp9_get_switchable_rate(cpi, xd) : 0;
     }
 
     if (!this_early_term) {
@@ -1364,6 +1361,8 @@ void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
           this_rdc.rate += vp9_get_switchable_rate(cpi, xd);
       }
     } else {
+      this_rdc.rate += cm->interp_filter == SWITCHABLE ?
+          vp9_get_switchable_rate(cpi, xd) : 0;
       this_rdc.rate += vp9_cost_bit(vp9_get_skip_prob(cm, xd), 1);
     }