Fix auto_report_temperatures()

The `auto_report_temperatures` needs a linefeed to be recognized by Repetier Host.

Marlin/Marlin_main.cpp

     if (auto_report_temp_interval && ELAPSED(millis(), next_temp_report_ms)) {
       next_temp_report_ms = millis() + 1000UL * auto_report_temp_interval;
       print_heaterstates();
+      SERIAL_EOL;
     }
   }