ARM: dts: imx6ul: Fix nand-controller #size-cells

nand-controller.yaml bindings says #size-cells shall be set to 0.
Fixes the dtbs_check warning:
arch/arm/boot/dts/nxp/imx/imx6ul-tqma6ul2l-mba6ulx.dtb:
 nand-controller@1806000: #size-cells:0:0: 0 was expected
 from schema $id: http://devicetree.org/schemas/mtd/gpmi-nand.yaml#Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/nxp/imx/imx6ul.dtsi

@@ -179,7 +179,7 @@ dma_apbh: dma-controller@1804000 {
 		gpmi: nand-controller@1806000 {
 			compatible = "fsl,imx6q-gpmi-nand";
 			#address-cells = <1>;
-			#size-cells = <1>;
+			#size-cells = <0>;
 			reg = <0x01806000 0x2000>, <0x01808000 0x2000>;
 			reg-names = "gpmi-nand", "bch";
 			interrupts = <0 15 IRQ_TYPE_LEVEL_HIGH>;