arm64: dts: qcom: sc8280xp: Add PS_HOLD restart

Killing the platform with a single write and no firmware involvement is
pretty cool, add support for it.

Note that due to restart notifier priority settings, PSCI reset will
be used instead, unless:

a) PSCI is not exposed by the firmware (e.g. because the fw was replaced)
or
b) PSCI restart fails for some reason
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240307-topic-8280_nodes-v1-3-4eba20e08902@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>

arch/arm64/boot/dts/qcom/sc8280xp.dtsi

@@ -4475,6 +4475,11 @@ tsens0: thermal-sensor@c263000 {
 			#thermal-sensor-cells = <1>;
 		};
 
+		restart@c264000 {
+			compatible = "qcom,pshold";
+			reg = <0 0x0c264000 0 0x4>;
+		};
+
 		tsens1: thermal-sensor@c265000 {
 			compatible = "qcom,sc8280xp-tsens", "qcom,tsens-v2";
 			reg = <0 0x0c265000 0 0x1ff>, /* TM */