netfilter: ebtables: Simplify the arguments to ebt_do_table

Nearly everything thing of interest to ebt_do_table is already present
in nf_hook_state.  Simplify ebt_do_table by just passing in the skb,
nf_hook_state, and the table.  This make the code easier to read and
maintenance easier.

To support this create an nf_hook_state on the stack in ebt_broute
(the only caller without a nf_hook_state already available).  This new
nf_hook_state adds no new computations to ebt_broute, but does use a
few more bytes of stack.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>