cls_bpf: also dump TCA_BPF_FLAGS

In commit 43388da42a49 ("cls_bpf: introduce integrated actions") we
have added TCA_BPF_FLAGS. We can also retrieve this information from
the prog, dump it back to user space as well. It's useful in tc when
displaying/dumping filter info.

Also, remove tp from cls_bpf_prog_from_efd(), came in as a conflict
from a rebase and it's unused here (later work may add it along with
a real user).

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>