of: add notes of critical trips for soctherm

The "critical" type trip in thermal zone can be
set to SOC_THERM hardware, it can trigger shut down
or reset event from hardware.
Signed-off-by: NWei Ni <wni@nvidia.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NEduardo Valentin <edubezval@gmail.com>

Documentation/devicetree/bindings/thermal/tegra-soctherm.txt

@@ -26,6 +26,10 @@ Required properties :
     of this property. See <dt-bindings/thermal/tegra124-soctherm.h> for a
     list of valid values when referring to thermal sensors.
 
+Note:
+- the "critical" type trip points will be set to SOC_THERM hardware as the
+shut down temperature. Once the temperature of this thermal zone is higher
+than it, the system will be shutdown or reset by hardware.
 
 Example :
 
@@ -51,5 +55,13 @@ Example: referring to thermal sensors :
 
                         thermal-sensors =
                                 <&soctherm TEGRA124_SOCTHERM_SENSOR_CPU>;
+
+			trips {
+				cpu_shutdown_trip: shutdown-trip {
+					temperature = <102500>;
+					hysteresis = <1000>;
+					type = "critical";
+				};
+			};
                 };
 	};