Fix Buzzer (pin) init for uninitialized FastIO (#19559)

Marlin/src/MarlinCore.cpp

@@ -1048,6 +1048,11 @@ void setup() {
   SERIAL_ECHO_MSG("Compiled: " __DATE__);
   SERIAL_ECHO_MSG(STR_FREE_MEMORY, freeMemory(), STR_PLANNER_BUFFER_BYTES, (int)sizeof(block_t) * (BLOCK_BUFFER_SIZE));
 
+  // Init buzzer pin(s)
+  #if USE_BEEPER
+    SETUP_RUN(buzzer.init());
+  #endif
+
   // Set up LEDs early
   #if HAS_COLOR_LEDS
     SETUP_RUN(leds.setup());

Marlin/src/libs/buzzer.h

@@ -84,9 +84,9 @@
 
     public:
       /**
-       * @brief Class constructor
+       * @brief Init Buzzer
        */
-      Buzzer() {
+      static inline void init() {
         SET_OUTPUT(BEEPER_PIN);
         reset();
       }