netfilter: nf_tables: dump NFTA_CHAIN_FLAGS attribute

commit d78008de6103c708171baff9650a7862645d23b0 upstream.

Missing NFTA_CHAIN_FLAGS netlink attribute when dumping basechain
definitions.

Fixes: c9626a2c ("netfilter: nf_tables: add hardware offload support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>