ARM: dts: imx53-ard: add regulators for lan9220

Since commit c7e963f6 (net/smsc911x: Add regulator support), the lan9220
device tree probe fails on imx53-ard board, because the commit makes
VDD33A and VDDVARIO supplies mandatory for the driver.

Add a fixed dummy 3V3 supplying lan9220 to fix the regression.

Cc: stable@vger.kernel.org
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

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

@@ -66,10 +66,30 @@ lan9220@f4000000 {
 			interrupt-parent = <&gpio2>;
 			interrupts = <31>;
 			reg-io-width = <4>;
+			/*
+			 * VDD33A and VDDVARIO of LAN9220 are supplied by
+			 * SW4_3V3 of LTC3589.  Before the regulator driver
+			 * for this PMIC is available, we use a fixed dummy
+			 * 3V3 regulator to get LAN9220 driver probing work.
+			 */
+			vdd33a-supply = <&reg_3p3v>;
+			vddvario-supply = <&reg_3p3v>;
 			smsc,irq-push-pull;
 		};
 	};
 
+	regulators {
+		compatible = "simple-bus";
+
+		reg_3p3v: 3p3v {
+			compatible = "regulator-fixed";
+			regulator-name = "3P3V";
+			regulator-min-microvolt = <3300000>;
+			regulator-max-microvolt = <3300000>;
+			regulator-always-on;
+		};
+	};
+
 	gpio-keys {
 		compatible = "gpio-keys";