Merge branch 'bpf: Add BPF_PROG_TYPE_CGROUP_SKB attach type enforcement in BPF_LINK_CREATE'

Stanislav Fomichev says:

====================
Syzkaller found a case where it's possible to attach cgroup_skb program
to the sockopt hooks. Apparently it's currently possible to do that,
but only when using BPF_LINK_CREATE API. The first patch in the series
has more info on why that happens.
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>