When replacing an IPv4 route, tb_id member of the new fib_alias
structure is not set in the replace code path so that the new route is
ignored.

Fixes: 0ddcf43d ("ipv4: FIB Local/MAIN table collapse")
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>