Fix ESP32 I2S init placement (#21019)

Marlin/src/HAL/ESP32/HAL.cpp

@@ -90,8 +90,6 @@ volatile int numPWMUsed = 0,
 
 #endif
 
-void HAL_init() { TERN_(I2S_STEPPER_STREAM, i2s_init()); }
-
 void HAL_init_board() {
 
   #if ENABLED(ESP3D_WIFISUPPORT)
@@ -126,6 +124,10 @@ void HAL_init_board() {
     #endif
   #endif
 
+  // Initialize the i2s peripheral only if the I2S stepper stream is enabled.
+  // The following initialization is performed after Serial1 and Serial2 are defined as
+  // their native pins might conflict with the i2s stream even when they are remapped.
+  TERN_(I2S_STEPPER_STREAM, i2s_init());
 }
 
 void HAL_idletask() {

Marlin/src/HAL/ESP32/HAL.h

@@ -139,7 +139,7 @@ void HAL_adc_start_conversion(const uint8_t adc_pin);
 #define HAL_IDLETASK 1
 #define BOARD_INIT() HAL_init_board();
 void HAL_idletask();
-void HAL_init();
+inline void HAL_init() {}
 void HAL_init_board();
 
 //