ARM: dts: add board specific fixed rate clock nodes for Exynos based platforms

The clock frequency of xxti and xusbxti clocks is dependent on the
frequency of the on-board oscillator that is used to generate these
clocks. So allow the frequency of these clocks to be specfied from
device tree.

Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
diff --git a/arch/arm/boot/dts/exynos5440-ssdk5440.dts b/arch/arm/boot/dts/exynos5440-ssdk5440.dts
index ee60c57..a21eb4c 100644
--- a/arch/arm/boot/dts/exynos5440-ssdk5440.dts
+++ b/arch/arm/boot/dts/exynos5440-ssdk5440.dts
@@ -27,4 +27,11 @@
 	spi {
 		status = "disabled";
 	};
+
+	fixed-rate-clocks {
+		xtal {
+			compatible = "samsung,clock-xtal";
+			clock-frequency = <50000000>;
+		};
+	};
 };