netfilter: nf_tables: rename nft_do_chain_pktinfo() to nft_do_chain()

We don't encode argument types into function names and since besides
nft_do_chain() there are only AF-specific versions, there is no risk
of confusion.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>