Use ADAPT_SCAN_PROB_PRECISION to init prob

Change-Id: I94d66c65d78235e1025703caf79ccca43208d604

av1/common/scan.c

diff --git a/av1/common/scan.c b/av1/common/scan.c
index 2076c8b..7bdeb62 100644
--- a/av1/common/scan.c
+++ b/av1/common/scan.c
@@ -6824,7 +6824,8 @@
       int i;
       SCAN_ORDER *sc = &cm->fc->sc[tx_size][tx_type];
       for (i = 0; i < tx2d_size; ++i) {
-        non_zero_prob[i] = (1 << 16) / 2;  // init non_zero_prob to 0.5
+        non_zero_prob[i] =
+            (1 << ADAPT_SCAN_PROB_PRECISION) / 2;  // init non_zero_prob to 0.5
       }
       update_scan_order_facade(cm, tx_size, tx_type);
       sc->scan = get_adapt_scan(cm->fc, tx_size, tx_type);