thermal: add getUndefinedTemperature function.

Bug: 34107726
Test: cts, vts
Change-Id: I8a3794158fbc0c9518a26f4616263aa464b43924
diff --git a/thermal/1.0/default/Thermal.cpp b/thermal/1.0/default/Thermal.cpp
index 8a8ad0a..5bc313d 100644
--- a/thermal/1.0/default/Thermal.cpp
+++ b/thermal/1.0/default/Thermal.cpp
@@ -169,6 +169,13 @@
   return Void();
 }
 
+Return<void> Thermal::getUndefinedTemperature(getUndefinedTemperature_cb _hidl_cb) {
+  ThermalStatus status;
+  status.code = ThermalStatusCode::SUCCESS;
+  _hidl_cb(status, UNKNOWN_TEMPERATURE);
+  return Void();
+}
+
 IThermal* HIDL_FETCH_IThermal(const char* /* name */) {
   thermal_module_t* module;
   status_t err = hw_get_module(THERMAL_HARDWARE_MODULE_ID,