Remove 'rddiv' member from various structs.

This was initialized from a const and never modified. But was still
passed around and stored in multiple structs.

Removed these 'rddiv' member variables and now RDOPT() and RDOPT_DBL()
always use the const RDDIV_BITS directly.

Change-Id: I1a8dfd2c8fa857d466ad1207b4f0dd6ec07eafb8
diff --git a/av1/encoder/picklpf.c b/av1/encoder/picklpf.c
index fc0ea48..5d166d3 100644
--- a/av1/encoder/picklpf.c
+++ b/av1/encoder/picklpf.c
@@ -154,8 +154,7 @@
   // Update best error
   best_err = ss_err[filt_best];
 
-  if (best_cost_ret)
-    *best_cost_ret = RDCOST_DBL(x->rdmult, x->rddiv, 0, best_err);
+  if (best_cost_ret) *best_cost_ret = RDCOST_DBL(x->rdmult, 0, best_err);
   return filt_best;
 }