r8152: fix rx issue for runtime suspend

Pause the rx and make sure the rx fifo is empty when the autosuspend
occurs.

If the rx data comes when the driver is canceling the rx urb, the host
controller would stop getting the data from the device and continue
it after next rx urb is submitted. That is, one continuing data is
split into two different urb buffers. That let the driver take the
data as a rx descriptor, and unexpected behavior happens.

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