ARM: dts: at91: sama5d2: add slow clock to watchdog node

As the watchdog timer needs the slow clock, add it to the currently defined
wdt node.
Reported-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>

arch/arm/boot/dts/sama5d2.dtsi

@@ -1050,6 +1050,7 @@
 				compatible = "atmel,sama5d4-wdt";
 				reg = <0xf8048040 0x10>;
 				interrupts = <4 IRQ_TYPE_LEVEL_HIGH 7>;
+				clocks = <&clk32k>;
 				status = "disabled";
 			};