Make filter creation in root table more flexible

Make filter creation in root table more flexible

Use the previously introduced chain priorities to sort the chains for access
from an interface's 'root' table and have them created in the proper order.
This gets rid of a lot of code that was previously creating the chains in a
more hardcoded way.

To determine what protocol a filter is used for evaluation do prefix-
matching, i.e., the filter 'arp' is used to filter for the 'arp' protocol,
'ipv4' for the 'ipv4' protocol and 'arp-xyz' will also be used to filter
for the 'arp' protocol following the prefix 'arp' in its name.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>