Refactor to use block_size_wide/high[] consistently

Replace the computation of block size in pixels with lookup table
directly.

Change-Id: I39589b2bc1d20372969ff5ad0f60639e64a19b41
diff --git a/av1/encoder/encodeframe.c b/av1/encoder/encodeframe.c
index 8540cc4..a768c1c 100644
--- a/av1/encoder/encodeframe.c
+++ b/av1/encoder/encodeframe.c
@@ -676,7 +676,7 @@
 
   if (bsize > leaf_size) {
     const BLOCK_SIZE subsize = get_subsize(bsize, PARTITION_SPLIT);
-    const int px = num_4x4_blocks_wide_lookup[subsize] * 4;
+    const int px = block_size_wide[subsize];
 
     init_variance_tree(vt->split[0],
 #if CONFIG_AOM_HIGHBITDEPTH