r8152: check RTL8152_UNPLUG and netif_running before autoresume

If the device is unplugged or !netif_running(), the workqueue
doesn't need to wake the device, and could return directly.

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