net: phy: realtek: enable ALDPS to save power for RTL8211F

Enable ALDPS(Advanced Link Down Power Saving) to save power when
link down.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>