cgroup-util: actually use the path callback

We allow to specify a callback but then ignore the result. Looks like a trivial typo.
From 7b3fd6313c4b07b6f822a9f979d0c22350a401d9#diff-f010fa21ba7b659b519c122743e55604

src/basic/cgroup-util.c

@@ -1776,7 +1776,7 @@ int cg_attach_everywhere(CGroupControllerMask supported, const char *path, pid_t
                         if (!p)
                                 p = path;
 
-                        cg_attach_fallback(n, path, pid);
+                        cg_attach_fallback(n, p, pid);
                 }
 
                 bit <<= 1;