AP_Baro: Use C_TO_KELVIN

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

libraries/AP_Baro/AP_Baro_HIL.cpp

@@ -88,7 +88,7 @@ void AP_Baro::setHIL(float altitude_msl)
 
     SimpleAtmosphere(altitude_msl*0.001f, sigma, delta, theta);
     float p = p0 * delta;
-    float T = 303.16f * theta - 273.16f; // Assume 30 degrees at sea level - converted to degrees Kelvin
+    float T = 303.16f * theta - C_TO_KELVIN; // Assume 30 degrees at sea level - converted to degrees Kelvin
 
     _hil.pressure = p;
     _hil.temperature = T;

libraries/AP_Baro/AP_Baro_SITL.cpp

@@ -105,14 +105,14 @@ void AP_Baro_SITL::_timer()
 
     AP_Baro::SimpleAtmosphere(sim_alt * 0.001f, sigma, delta, theta);
     float p = p0 * delta;
-    float T = 303.16f * theta - 273.16f;  // Assume 30 degrees at sea level - converted to degrees Kelvin
+    float T = 303.16f * theta - C_TO_KELVIN;  // Assume 30 degrees at sea level - converted to degrees Kelvin
 
     temperature_adjustment(p, T);
 #else
     float rho, delta, theta;
     AP_Baro::SimpleUnderWaterAtmosphere(-sim_alt * 0.001f, rho, delta, theta);
     float p = p0 * delta;
-    float T = 303.16f * theta - 273.16f;  // Assume 30 degrees at sea level - converted to degrees Kelvin
+    float T = 303.16f * theta - C_TO_KELVIN;  // Assume 30 degrees at sea level - converted to degrees Kelvin
 #endif
 
     _recent_press = p;

libraries/AP_Baro/AP_Baro_UAVCAN.cpp

@@ -82,7 +82,7 @@ void AP_Baro_UAVCAN::handle_baro_msg(float pressure, float temperature)
 {
     if (_sem_baro->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         _pressure = pressure;
-        _temperature = temperature - 273.15f;
+        _temperature = temperature - C_TO_KELVIN;
         _last_timestamp = AP_HAL::micros64();
         _sem_baro->give();
     }