[EBTABLES]: Clean ebt_get_udc_positions() up.

Check for valid_hooks is redundant (newinfo->hook_entry[i] will
be NULL if bit i is not set).  Kill it, kill unused arguments.

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