ARM: dts: imx6qdl-gw51xx: Remove unneeded #address-cells/#size-cells

The following dtc warning is seen when building with W=1:

arch/arm/boot/dts/imx6qdl-gw51xx.dtsi:23.12-68.4: Warning (avoid_unnecessary_addr_size): /gpio-keys: unnecessary #address-cells/#size-cells without "ranges" or child "reg" property

Remove the unneeded #address-cells/#size-cells properties to fix the issue.

Fixes: 64bf0a0a

 ("ARM: dts: imx6qdl-gw: add Gateworks System Controller support")
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>