ARM: dts: imx6sx: correct i.MX6sx sdb board enet phy address

The commit (3d125f9c) cause i.MX6SX sdb enet cannot work. The cause is
the commit add mdio node with un-correct phy address.

The patch just correct i.MX6sx sdb board enet phy address.

V2:
* As Shawn's suggestion that unit-address should match 'reg' property, so
  update ethernet-phy unit-address.
Acked-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NFugang Duan <B38611@freescale.com>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/arm/boot/dts/imx6sx-sdb.dts

@@ -166,12 +166,12 @@ mdio {
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		ethphy1: ethernet-phy@0 {
-			reg = <0>;
+		ethphy1: ethernet-phy@1 {
+			reg = <1>;
 		};
 
-		ethphy2: ethernet-phy@1 {
-			reg = <1>;
+		ethphy2: ethernet-phy@2 {
+			reg = <2>;
 		};
 	};
 };