utils/kamcmd: fix memory leak

fixes #3478

utils/kamcmd/kamcmd.c

@@ -1395,6 +1395,8 @@ void free_cfg_grp_lst()
 	while(grp) {
 		last = grp;
 		grp = grp->next;
+		if(last->var_names)
+			free(last->var_names);
 		free(last);
 	}
 	cfg_grp_lst = 0;