arm64: dts: juno: drop unnecessary address-cells and size-cells properties

/smb@8000000/motherboard/gpio_keys node doesn't have "ranges" or "reg"
property in child nodes. So it's unnecessary to have address-cells
as well as size-cells properties which results in below warning.

Warning (avoid_unnecessary_addr_size):
/smb@8000000/motherboard/gpio_keys:
	unnecessary #address-cells/#size-cells without "ranges" or child "reg"
	property

This patch drops the unnecessary address+size-cell properties.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

arch/arm64/boot/dts/arm/juno-motherboard.dtsi

@@ -56,8 +56,6 @@ mb_fixed_3v3: mcc-sb-3v3 {
 
 			gpio_keys {
 				compatible = "gpio-keys";
-				#address-cells = <1>;
-				#size-cells = <0>;
 
 				power-button {
 					debounce_interval = <50>;