r8152: fix the carrier off when autoresuming

netif_carrier_off would be called when autoresuming, even though
the cable is plugged. This causes some applications do relative
actions when detecting the carrier off. Keep the status of the
carrier, and let it be modified when the linking change occurs.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>