r8152: remove the setting of LAN_WAKE_EN

The LAN_WAKE_EN is not used to determine if the device could support
WOL. It is used to signal a GPIO pin when a WOL event occurs. The WOL
still works even though it is disabled.

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