arm64: dts: imx8dxl-evk: Remove invalid SPI property

'pinctrl-assert-gpios' is not a valid property.

Remove it to fix the following schema warning:

imx8dxl-evk.dtb: spi@5a030000: Unevaluated properties are not allowed ('pinctrl-assert-gpios' was unexpected)
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8dxl-evk.dts

@@ -365,7 +365,6 @@ &lpspi3 {
 	fsl,spi-only-use-cs1-sel;
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_lpspi3>;
-	pinctrl-assert-gpios = <&pca6416_1 7 GPIO_ACTIVE_HIGH>;
 	status = "okay";
 
 	spidev0: spi@0 {