bpf: Remove tst_run from lwt_seg6local_prog_ops.

The syzbot reported that the lwt_seg6 related BPF ops can be invoked
via bpf_test_run() without without entering input_action_end_bpf()
first.

Martin KaFai Lau said that self test for BPF_PROG_TYPE_LWT_SEG6LOCAL
probably didn't work since it was introduced in commit 04d4b274e2a
("ipv6: sr: Add seg6local action End.BPF"). The reason is that the
per-CPU variable seg6_bpf_srh_states::srh is never assigned in the self
test case but each BPF function expects it.

Remove test_run for BPF_PROG_TYPE_LWT_SEG6LOCAL.

[ bigeasy: Also revert "seg6: Ensure that seg6_bpf_srh_states can only
  be accessed from input_action_end_bpf()" ]

Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
Reported-by:  <syzbot+608a2acde8c5a101d07d@syzkaller.appspotmail.com>
Fixes: d1542d4ae4df ("seg6: Use nested-BH locking for seg6_bpf_srh_states.")
Fixes: 004d4b27

 ("ipv6: sr: Add seg6local action End.BPF")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240710141631.FbmHcQaX@linutronix.de
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>