bpf, cgroups: clean up kerneldoc warnings

Building with W=1 reveals some bitrot:

  CC      kernel/bpf/cgroup.o
kernel/bpf/cgroup.c:238: warning: Function parameter or member 'flags' not described in '__cgroup_bpf_attach'
kernel/bpf/cgroup.c:367: warning: Function parameter or member 'unused_flags' not described in '__cgroup_bpf_detach'

Add a kerneldoc line for 'flags'.

Fixing the warning for 'unused_flags' is best approached by
removing the unused parameter on the function call.

Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

kernel/bpf/cgroup.c

@@ -230,6 +230,7 @@ cleanup:
  * @cgrp: The cgroup which descendants to traverse
  * @prog: A program to attach
  * @type: Type of attach operation
+ * @flags: Option flags
  *
  * Must be called with cgroup_mutex held.
  */
@@ -363,7 +364,7 @@ cleanup:
  * Must be called with cgroup_mutex held.
  */
 int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
-			enum bpf_attach_type type, u32 unused_flags)
+			enum bpf_attach_type type)
 {
 	struct list_head *progs = &cgrp->bpf.progs[type];
 	enum bpf_cgroup_storage_type stype;