ARM64: zynqmp: clk: Add the clock for watchdog

The watchdog clock node is missing.
Add the same. This solves the below error.

cdns-wdt fd4d0000.watchdog: input clock not found
cdns-wdt: probe of fd4d0000.watchdog failed with error -2
Signed-off-by: NShubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>

arch/arm/dts/zynqmp-clk.dtsi

@@ -218,6 +218,10 @@
 	clocks = <&clk250>, <&clk250>;
 };
 
+&watchdog0 {
+	clocks = <&clk250>;
+};
+
 &xilinx_drm {
 	clocks = <&drm_clock>;
 };