[EBTABLES]: Split ebt_check_entry_size_and_hooks

Split ebt_check_entry_size_and_hooks() in two parts - one that does
sanity checks on pointers (basically, checks that we can safely
use iterator from now on) and the rest of it (looking into details
of entry).

The loop applying ebt_check_entry_size_and_hooks() is split in two.

Populating newinfo->hook_entry[] is done in the first part.

Unused arguments killed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>