soreuseport: add compat case for setsockopt SO_ATTACH_REUSEPORT_CBPF

Commit 538950a1 ("soreuseport: setsockopt SO_ATTACH_REUSEPORT_[CE]BPF")
missed to add the compat case for the SO_ATTACH_REUSEPORT_CBPF option.

Signed-off-by: Helge Deller <deller@gmx.de>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>