r8152: fix the runtime suspend issues

Fix the runtime suspend issues result from the linking change.

Case 1:
a) link down occurs.
b) driver disable tx/rx.
c) autosuspend occurs.
d) hw linking up.
e) device suspends without enabling tx/rx.
f) couldn't wake up when receiving packets.

Case 2:
a) Nway results in linking down.
b) autosuspend occurs.
c) device suspends.
d) device may not wake up when linking up.

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