ARM: dts: imx53-cx9020: Fix the Ethernet PHY reset GPIO polarity

As explained in Documentation/devicetree/bindings/net/fsl-fec.txt the
phy-reset-gpios is active high only if the 'phy-reset-active-high' is
present.

As 'phy-reset-active-high' is not used here, fix the device tree
description by passing GPIO_ACTIVE_LOW flag.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Tested-by: Patrick Bruenn <p.bruenn@beckhoff.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx53-cx9020.dts

@@ -152,7 +152,7 @@ &fec {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_fec>;
 	phy-mode = "rmii";
-	phy-reset-gpios = <&gpio7 6 GPIO_ACTIVE_HIGH>;
+	phy-reset-gpios = <&gpio7 6 GPIO_ACTIVE_LOW>;
 	status = "okay";
 };