simulator: Use baro pressure direct from simulator

src/modules/simulator/simulator_mavlink.cpp

@@ -245,8 +245,10 @@ void Simulator::update_sensors(mavlink_hil_sensor_t *imu)
 	perf_begin(_perf_mag);
 
 	RawBaroData baro = {};
-	// calculate air pressure from altitude (valid for low altitude)
-	baro.pressure = (PRESS_GROUND - CONSTANTS_ONE_G * DENSITY * imu->pressure_alt) / 100.0f; // convert from Pa to mbar
+
+	// Get air pressure and pressure altitude
+	// valid for troposphere (below 11km AMSL)
+	baro.pressure = imu->abs_pressure;
 	baro.altitude = imu->pressure_alt;
 	baro.temperature = imu->temperature;