Change model type for tx search prune

A slight speed improvement and a little improvevent in
BDRATE for midres.

midres (20 frames): -0.049%
lowres (20 frames): +0.008%

The surface fit model will be replaced/removed subsequently.

STATS_CHANGED

Change-Id: Ide33f8d8ec27c5a6fd93b5630d1cfaeaec2ab436
diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index 9bc6ea2..3acc50b 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -150,7 +150,7 @@
 // 3: DNN regression model
 // 4: Full rd model
 #define MODELRD_TYPE_INTERP_FILTER 1
-#define MODELRD_TYPE_TX_SEARCH_PRUNE 2
+#define MODELRD_TYPE_TX_SEARCH_PRUNE 1
 #define MODELRD_TYPE_MASKED_COMPOUND 1
 #define MODELRD_TYPE_INTERINTRA 1
 #define MODELRD_TYPE_INTRA 1