tone_alarm: add GPS warning tone

src/drivers/drv_tone_alarm.h

@@ -144,6 +144,7 @@ enum {
 	TONE_ARMING_WARNING_TUNE,
 	TONE_BATTERY_WARNING_SLOW_TUNE,
 	TONE_BATTERY_WARNING_FAST_TUNE,
+	TONE_GPS_WARNING_TUNE,
 	TONE_NUMBER_OF_TUNES
 };
 

src/drivers/stm32/tone_alarm/tone_alarm.cpp

@@ -333,6 +333,7 @@ ToneAlarm::ToneAlarm() :
 	_default_tunes[TONE_ARMING_WARNING_TUNE] = "MNT75L1O2G";					//arming warning
 	_default_tunes[TONE_BATTERY_WARNING_SLOW_TUNE] = "MBNT100a8";					//battery warning slow
 	_default_tunes[TONE_BATTERY_WARNING_FAST_TUNE] = "MBNT255a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8a8";	//battery warning fast
+	_default_tunes[TONE_GPS_WARNING_TUNE] = "MFT255L4AAAL1F#";					//gps warning slow
 
 	_tune_names[TONE_STARTUP_TUNE] = "startup";			// startup tune
 	_tune_names[TONE_ERROR_TUNE] = "error";				// ERROR tone
@@ -342,6 +343,7 @@ ToneAlarm::ToneAlarm() :
 	_tune_names[TONE_ARMING_WARNING_TUNE] = "arming";		// arming warning
 	_tune_names[TONE_BATTERY_WARNING_SLOW_TUNE] = "slow_bat";	// battery warning slow
 	_tune_names[TONE_BATTERY_WARNING_FAST_TUNE] = "fast_bat";	// battery warning fast
+	_tune_names[TONE_GPS_WARNING_TUNE] = "gps_warning";	            // gps warning
 }
 
 ToneAlarm::~ToneAlarm()