ARM: at91/dt: usb_a9260: define crystals frequencies

Define Calao USB-A9260, USB-A9G20 and USB-A9G20-LPW main and slow crystals
frequencies.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/usb_a9260_common.dtsi

@@ -16,6 +16,14 @@
 			compatible = "atmel,osc", "fixed-clock";
 			clock-frequency = <12000000>;
 		};
+
+		slow_xtal {
+			clock-frequency = <32768>;
+		};
+
+		main_xtal {
+			clock-frequency = <12000000>;
+		};
 	};
 
 	ahb {