ARM: dts: imx27: use label to override osc26m clock setting

Instead of copying the whole node hierarchy, let's define a label for
clock osc26m in soc dtsi and use it for overriding clock-frequency.
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx27-apf27.dts

@@ -22,17 +22,10 @@
 	memory@a0000000 {
 		reg = <0xa0000000 0x04000000>;
 	};
+};
 
-	clocks {
-		#address-cells = <1>;
-		#size-cells = <0>;
-
-		osc26m {
-			compatible = "fsl,imx-osc26m", "fixed-clock";
-			#clock-cells = <0>;
-			clock-frequency = <0>;
-		};
-	};
+&clk_osc26m {
+	clock-frequency = <0>;
 };
 
 &iomuxc {

arch/arm/boot/dts/imx27.dtsi

@@ -57,7 +57,7 @@
 	};
 
 	clocks {
-		osc26m {
+		clk_osc26m: osc26m {
 			compatible = "fsl,imx-osc26m", "fixed-clock";
 			#clock-cells = <0>;
 			clock-frequency = <26000000>;