netfilter: nf_tables: explicit nft_set_pktinfo() call from hook path

Instead of calling this function from the family specific variant, this
reduces the code size in the fast path for the netdev, bridge and inet
families. After this change, we must call nft_set_pktinfo() upfront from
the chain hook indirection.

Before:

   text    data     bss     dec     hex filename
   2145     208       0    2353     931 net/netfilter/nf_tables_netdev.o

After:

   text    data     bss     dec     hex filename
   2125     208       0    2333     91d net/netfilter/nf_tables_netdev.o

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>