remove unnecessary 'if'

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@4402 65c4cc65-6c06-0410-ace0-fbb531ad65f3

ast_expr.y

@@ -215,8 +215,7 @@ struct val *vp;
 	}
 	if (vp->type == string || vp->type == numeric_string)
 		free (vp->u.s);	
-	if (vp)
-		free (vp);
+	free (vp);
 }