clean up some warnings when building recovery

Change-Id: I1541534ee6978ddf8d548433986679ce9507d508
diff --git a/updater/updater.c b/updater/updater.c
index 4e1cc9c..b7af3e5 100644
--- a/updater/updater.c
+++ b/updater/updater.c
@@ -105,8 +105,7 @@
 
     Expr* root;
     int error_count = 0;
-    yy_scan_string(script);
-    int error = yyparse(&root, &error_count);
+    int error = parse_string(script, &root, &error_count);
     if (error != 0 || error_count > 0) {
         printf("%d parse errors\n", error_count);
         return 6;