vp9_entropy: delete vp9_coefmodel_tree[]

it's been unused since:
4ac6a25 Moving vp9_tree_probs_from_distribution() to encoder.

Change-Id: Ieae65864277fc3dbe993c5c08d75c6c5fcaa3a2d

vp9/common/vp9_entropy.c

@@ -133,12 +133,6 @@ const uint8_t vp9_pt_energy_class[ENTROPY_TOKENS] = {
   0, 1, 2, 3, 3, 4, 4, 5, 5, 5, 5, 5
 };
 
-const vp9_tree_index vp9_coefmodel_tree[TREE_SIZE(UNCONSTRAINED_NODES + 1)] = {
-  -EOB_MODEL_TOKEN, 2,
-  -ZERO_TOKEN, 4,
-  -ONE_TOKEN, -TWO_TOKEN,
-};
-
 // Model obtained from a 2-sided zero-centerd distribuition derived
 // from a Pareto distribution. The cdf of the distribution is:
 // cdf(x) = 0.5 + 0.5 * sgn(x) * [1 - {alpha/(alpha + |x|)} ^ beta]

vp9/common/vp9_entropy.h

@@ -74,7 +74,6 @@ DECLARE_ALIGNED(16, extern const uint8_t, vp9_cat6_prob_high12[18]);
 #endif  // CONFIG_VP9_HIGHBITDEPTH
 
 #define EOB_MODEL_TOKEN 3
-extern const vp9_tree_index vp9_coefmodel_tree[];
 
 typedef struct {
   const vp9_tree_index *tree;