ARM: dts: uniphier: add reference clock nodes

Add master clock nodes generated by crystal oscillators.

  PH1-sLD3, PH1-LD4: 24.576 MHz
  PH1-Pro4, ProXstream2: 25.000 MHz
  PH1-Pro5: 20.000 MHz

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/dts/uniphier-ph1-pro5.dtsi b/arch/arm/dts/uniphier-ph1-pro5.dtsi
index 0049106..120767c 100644
--- a/arch/arm/dts/uniphier-ph1-pro5.dtsi
+++ b/arch/arm/dts/uniphier-ph1-pro5.dtsi
@@ -171,6 +171,10 @@
 	};
 };
 
+&refclk {
+	clock-frequency = <20000000>;
+};
+
 &serial0 {
 	clock-frequency = <73728000>;
 };