Update SYS_CAL_TEMP parameter name and description

We will be adding another parameter to set min starting temp, so this name needs to be made less generic.
Fixes typographical errors in the description

src/modules/events/temperature_calibration/task.cpp

@@ -124,7 +124,7 @@ void TemperatureCalibration::task_main()
 	}
 
 	int32_t min_temp_rise = 24;
-	param_get(param_find("SYS_CAL_TEMP"), &min_temp_rise);
+	param_get(param_find("SYS_CAL_TDEL"), &min_temp_rise);
 	PX4_INFO("Waiting for %i degrees difference in sensor temperature", min_temp_rise);
 
 	//init calibrators

src/modules/systemlib/system_params.c

@@ -212,13 +212,12 @@ PARAM_DEFINE_INT32(SYS_CAL_BARO, 0);
 /**
  * Required temperature rise during thermal calibration
  *
- * A temperature increase greater than this value is required during calibration performed by the setting of SYS_TEMP_CAL.
+ * A temperature increase greater than this value is required during calibration.
- * Calibration will complete for each sensor when the temperature increase above the starting temeprature exceeds SYS_TEMP_RISE.
+ * Calibration will complete for each sensor when the temperature increase above the starting temeprature exceeds the value set by SYS_CAL_TDEL.
  * If the temperature rise is insufficient, the calibration will continue indefinitely and the board will need to be repowered to exit.
  *
  * @unit deg C
  * @min 10
- * @max 50
  * @group System
  */
-PARAM_DEFINE_INT32(SYS_CAL_TEMP, 24);
+PARAM_DEFINE_INT32(SYS_CAL_DELT, 24);