subnet. Fix that
by deleting local and broadcast routes for all secondaries while
they are on device list and by faking that all addresses from
this subnet are to be deleted. It relies on fib_del_ifaddr being
able to ignore the IPs from the concerned subnet while checking
for duplication.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>