[NETNS]: Pass fib_rules_ops into default_pref method.

fib_rules_ops contains operations and the list of configured rules. ops will
become per/namespace soon, so we need them to be known in the default_pref
callback.

Acked-by: Benjamin Thery <benjamin.thery@bull.net>
Acked-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>