[IPV4]: no need pass pointer to a default into fib_detect_death

ipv4: no need pass pointer to a default into fib_detect_death

Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>