encodetxb.c: remove dead local variables.

Change-Id: Ia5db8df366769640fc90632fd22e55fbd00ac0d7
diff --git a/av1/encoder/encodetxb.c b/av1/encoder/encodetxb.c
index 4b1bfe0..28cc0c7 100644
--- a/av1/encoder/encodetxb.c
+++ b/av1/encoder/encodetxb.c
@@ -1308,10 +1308,6 @@
                               txb_ctx->dc_sign_ctx);
 
     if (abs_qc > NUM_BASE_LEVELS) {
-      const int row = pos >> txb_info->bwl;
-      const int col = pos - (row << txb_info->bwl);
-
-      (void)col;
       const int ctx =
           get_br_ctx(txb_info->levels, pos, txb_info->bwl, txb_info->tx_type);
       cost += get_br_cost(abs_qc, ctx, txb_costs->lps_cost[ctx]);