Merge pull request #1969 from thinkyhead/buzz_duration

Fix BEEPER duration

Marlin/ultralcd.cpp

@@ -1545,6 +1545,7 @@ void lcd_buzz(long duration, uint16_t freq) {
     #if BEEPER > 0
       SET_OUTPUT(BEEPER);
       tone(BEEPER, freq, duration);
+      delay(duration);
     #elif defined(LCD_USE_I2C_BUZZER)
       lcd.buzz(duration, freq);
     #else