net: netfilter: Remove ifdefs for code shared by BPF and ctnetlink

The current ifdefry for code shared by the BPF and ctnetlink side looks
ugly. As per Pablo's request, simplify this by unconditionally compiling
in the code. This can be revisited when the shared code between the two
grows further.

Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220725085130.11553-1-memxor@gmail.com


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