ARM: dts: imx7ulp: Fix 'assigned-clocks-parents' typo

The correct property name is 'assigned-clock-parents', not
'assigned-clocks-parents'. Though if the platform works with the typo, one
has to wonder if the property is even needed.
Signed-off-by: NRob Herring <robh@kernel.org>
Fixes: 8b8c7d97 ("ARM: dts: imx7ulp: Add wdog1 node")
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7ulp.dtsi

@@ -259,7 +259,7 @@
 			interrupts = <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>;
 			clocks = <&pcc2 IMX7ULP_CLK_WDG1>;
 			assigned-clocks = <&pcc2 IMX7ULP_CLK_WDG1>;
-			assigned-clocks-parents = <&scg1 IMX7ULP_CLK_FIRC_BUS_CLK>;
+			assigned-clock-parents = <&scg1 IMX7ULP_CLK_FIRC_BUS_CLK>;
 			timeout-sec = <40>;
 		};