Fix BTT002 SPEAKER timer conflict (#18011)

buildroot/share/PlatformIO/variants/BIGTREE_BTT002/variant.h

 
 // Timer Definitions
 //Do not use timer used by PWM pins when possible. See PinMap_PWM in PeripheralPins.c
-#define TIMER_TONE              TIM6
-#define TIMER_SERIAL            TIM7
-
-// Do not use basic timer: OC is required
-#define TIMER_SERVO             TIM2  //TODO: advanced-control timers don't work
+#define TIMER_TONE              TIM7
+#define TIMER_SERVO             TIM5
+#define TIMER_SERIAL            TIM2
 
 // UART Definitions
 // Define here Serial instance number to map on Serial generic name