ARM: dts: imx6qdl-sabresd: enable fec wake-on-lan

Enable ethernet wake-on-lan feature for imx6q/dl/qp sabresd
boards since the PHY clock is supplied by external osc.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>