arm64: dts: qcom: sm6375-pdx225: Add volume down GPIO key

Add the required nodes to enable the volume down key on the Sony
Xperia 10 IV.
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230303-topic-sm6375_features0_dts-v2-14-708b8191f7eb@linaro.org

arch/arm64/boot/dts/qcom/sm6375-sony-xperia-murray-pdx225.dts

@@ -46,6 +46,23 @@ framebuffer: framebuffer@85200000 {
 		};
 	};
 
+	gpio-keys {
+		compatible = "gpio-keys";
+		label = "gpio-keys";
+
+		pinctrl-0 = <&vol_down_n>;
+		pinctrl-names = "default";
+
+		key-volume-down {
+			label = "Volume Down";
+			linux,code = <KEY_VOLUMEDOWN>;
+			gpios = <&pmr735a_gpios 1 GPIO_ACTIVE_LOW>;
+			debounce-interval = <15>;
+			linux,can-disable;
+			wakeup-source;
+		};
+	};
+
 	reserved-memory {
 		cont_splash_mem: memory@85200000 {
 			reg = <0 0x85200000 0 0xc00000>;
@@ -133,6 +150,16 @@ &pmk8350_rtc {
 	status = "okay";
 };
 
+&pmr735a_gpios {
+	vol_down_n: vol-down-n-state {
+		pins = "gpio1";
+		function = "normal";
+		power-source = <1>;
+		bias-pull-up;
+		input-enable;
+	};
+};
+
 &pon_pwrkey {
 	status = "okay";
 };