ARM: dts: imx6q-var-dt6customboard: Remove #address/#size-cells from gpio-keys

Remove unnecessary #address-cells/#size-cells to fix the following
DTC warning:

arch/arm/boot/dts/imx6q-var-dt6customboard.dtb: Warning (avoid_unnecessary_addr_size): /gpio-keys: unnecessary #address-cells/#size-cells without "ranges" or child "reg" property
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6q-var-dt6customboard.dts

@@ -26,8 +26,6 @@ backlight_lvds: backlight {
 
 	gpio-keys {
 		compatible = "gpio-keys";
-		#address-cells = <1>;
-		#size-cells = <0>;
 		autorepeat;
 
 		back {