Some necessary sepolicy rule changes for init process to create directory,
mount cgroupv2 module and mount bpf filesystem. Also allow netd to create
and pin bpf object as files and read it back from file under the
directory where bpf filesystem is mounted.

Test: bpf maps show up under /sys/fs/bpf/
Change-Id: I579d04f60d7e20bd800d970cd28cd39fda9d20a0