arm64: dts: apm: drop unused reg-io-width from DW APB GPIO controller

The Synopsys DesignWare APB GPIO controller driver does not parse
reg-io-width and dtschema does not allow it so drop it to fix dtschema
warnings like:

  arch/arm64/boot/dts/apm/apm-mustang.dt.yaml: gpio@1c024000:
    'reg-io-width' does not match any of the regexes: '^gpio-(port|controller)@[0-9a-f]+$', 'pinctrl-[0-9]+'

Link: https://lore.kernel.org/r/20200917165040.22908-1-krzk@kernel.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm64/boot/dts/apm/apm-shadowcat.dtsi

@@ -709,7 +709,6 @@
 		dwgpio: gpio@1c024000 {
 			compatible = "snps,dw-apb-gpio";
 			reg = <0x0 0x1c024000 0x0 0x1000>;
-			reg-io-width = <4>;
 			#address-cells = <1>;
 			#size-cells = <0>;
 

arch/arm64/boot/dts/apm/apm-storm.dtsi

@@ -825,7 +825,6 @@
 		dwgpio: gpio@1c024000 {
 			compatible = "snps,dw-apb-gpio";
 			reg = <0x0 0x1c024000 0x0 0x1000>;
-			reg-io-width = <4>;
 			#address-cells = <1>;
 			#size-cells = <0>;