Merge branch 'Refactor cgroup_bpf internals to use more specific attach_type'

Dave Marchevsky says:

====================

The cgroup_bpf struct has a few arrays (effective, progs, and flags) of
size MAX_BPF_ATTACH_TYPE. These are meant to separate progs by their
attach type, currently represented by the bpf_attach_type enum.

There are some bpf_attach_type values which are not valid attach types
for cgroup bpf programs. Programs with these attach types will never be
handled by cgroup_bpf_{attach,detach} and thus will never be held in
cgroup_bpf structs. Even if such programs did make it into their
reserved slot in those arrays, they would never be executed.

Accordingly we can migrate to a new internal cgroup_bpf-specific enum
for these arrays, saving some bytes per cgroup and making it more
obvious which BPF programs belong there. netns_bpf_attach_type is an
existing example of this pattern, let's do similar for cgroup_bpf.

v1->v2: Address Daniel's comments
* Reverse xmas tree ordering for def changes
* Helper macro to reduce to_cgroup_bpf_attach_type boilerplate
* checkpatch.pl complains: "ERROR: Macros with complex values should
be enclosed in parentheses". Found some existing macros (do 'git grep
"define case"') which get same complaint. Think it's fine to keep
as-is since it's immediately undef'd.
* Remove CG_BPF_ prefix from cgroup_bpf_attach_type
* Although I agree that the prefix is redundant, the de-prefixed
names feel a bit too 'general' given the internal use of the enum.
e.g. when someone sees CGROUP_INET6_BIND it's not obvious that it
should only be used in certain ways internally.
* Don't feel strongly about this, just my thoughts as a noob to the
internals.
* Rebase onto latest bpf-next/master
* No significant conflicts, some small boilerplate adjustments
needed to catch up to Andrii's "bpf: Refactor BPF_PROG_RUN_ARRAY
family of macros into functions" change
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>