r8169: fix kernel log spam when set or get hardware wol setting.

NIC will be put into D3 state during runtime suspend state. When set or
get hardware wol setting, driver will write or read hardware registers.
If we set or get hardware wol setting in runtime suspend state, because
NIC will in D3 state, the hardware registers read by driver will return all
0xff. That will let driver thinking register flag is not toggled and
then prints the warning message "rtl_counters_cond == 1 (loop: 1000,
delay: 10)" to kernel log.

For fixing this issue, add checking driver's pm runtime status in
rtl8169_get_wol() and rtl8169_set_wol().

Signed-off-by: Chunhao Lin <hau@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>