cgroup-util: drop 'controller' argument from cg_get_path()

The argument is not used anymore. Let's drop it.

src/shared/condition.c

@@ -1110,7 +1110,7 @@ static int condition_test_psi(Condition *c, char **env) {
                         free_and_replace(slice_path, slice_joined);
                 }
 
-                r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, slice_path, controller, &pressure_path);
+                r = cg_get_path(slice_path, controller, &pressure_path);
                 if (r < 0)
                         return log_debug_errno(r, "Error getting cgroup pressure path from %s: %m", slice_path);