arm64: dts: lx2160a: specify clock frequencies for the MDIO controllers

Up until now, the external MDIO controller frequency values relied
either on the default ones out of reset or on those setup by u-boot.
Let's just properly specify the MDC frequency in the DTS so that even
without u-boot's intervention Linux can drive the MDIO bus.

Fixes: 6e1b8fae ("arm64: dts: lx2160a: add emdio1 node")
Fixes: 5705b9dc ("arm64: dts: lx2160a: add emdio2 node")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/fsl-lx2160a.dtsi

@@ -1385,6 +1385,9 @@ emdio1: mdio@8b96000 {
 			#address-cells = <1>;
 			#size-cells = <0>;
 			little-endian;
+			clock-frequency = <2500000>;
+			clocks = <&clockgen QORIQ_CLK_PLATFORM_PLL
+					    QORIQ_CLK_PLL_DIV(2)>;
 			status = "disabled";
 		};
 
@@ -1395,6 +1398,9 @@ emdio2: mdio@8b97000 {
 			little-endian;
 			#address-cells = <1>;
 			#size-cells = <0>;
+			clock-frequency = <2500000>;
+			clocks = <&clockgen QORIQ_CLK_PLATFORM_PLL
+					    QORIQ_CLK_PLL_DIV(2)>;
 			status = "disabled";
 		};