ARM: dts: sam9x60ek: add clock frequencies to board file

Slow Xtal and Main Xtal are board specific. Add their proper
frequency to board file.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
diff --git a/arch/arm/dts/sam9x60ek.dts b/arch/arm/dts/sam9x60ek.dts
index 8767de9..44af5d9 100644
--- a/arch/arm/dts/sam9x60ek.dts
+++ b/arch/arm/dts/sam9x60ek.dts
@@ -18,6 +18,16 @@
 		i2c0 = &flx0;
 	};
 
+	clocks {
+		slow_xtal: slow_xtal {
+			clock-frequency = <32768>;
+		};
+
+		main_xtal: main_xtal {
+			clock-frequency = <24000000>;
+		};
+	};
+
 	onewire_tm: onewire {
 		gpios = <&pioD 14 0>;
 		pinctrl-names = "default";