arm64: dts: imx8dxl-evk: Remove 'fsl,spi-num-chipselects'

The 'fsl,spi-num-chipselects' property is not a valid one, so remove it.
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

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

@@ -362,7 +362,6 @@ &usdhc2 {
 };
 
 &lpspi3 {
-	fsl,spi-num-chipselects = <1>;
 	fsl,spi-only-use-cs1-sel;
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_lpspi3>;