bpf: cgroup: annotate pointers in struct cgroup_bpf with __rcu

The member 'effective' in 'struct cgroup_bpf' is protected by RCU.
Annotate it accordingly to squelch a sparse warning.
Signed-off-by: Daniel Mack <daniel@zonque.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/bpf-cgroup.h

@@ -20,7 +20,7 @@ struct cgroup_bpf {
 	 * when this cgroup is accessed.
 	 */
 	struct bpf_prog *prog[MAX_BPF_ATTACH_TYPE];
-	struct bpf_prog *effective[MAX_BPF_ATTACH_TYPE];
+	struct bpf_prog __rcu *effective[MAX_BPF_ATTACH_TYPE];
 };
 
 void cgroup_bpf_put(struct cgroup *cgrp);