ARM: at91/dt: usb_a9263: define crystals frequencies

Define Calao USB-A9263 main and slow crystals frequencies.
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/usb_a9263.dts

@@ -29,6 +29,14 @@
 			compatible = "atmel,osc", "fixed-clock";
 			clock-frequency = <12000000>;
 		};
+
+		slow_xtal {
+			clock-frequency = <32768>;
+		};
+
+		main_xtal {
+			clock-frequency = <12000000>;
+		};
 	};
 
 	ahb {