netfilter: nftables: update table flags from the commit phase

commit 0ce7cf4127f14078ca598ba9700d813178a59409 upstream.

Do not update table flags from the preparation phase. Store the flags
update into the transaction, then update the flags from the commit
phase.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>