Exclude duplicated checking for iface-up. This flags is checked in...

Exclude duplicated checking for iface-up. This flags is checked in 'is_skb_forwardable' function, which is subroutine of 'dev_forward_skb'.

Signed-off-by: Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>