Fix Arduino DUE compilation (#20058)

Marlin/src/HAL/STM32/MarlinSPI.cpp

@@ -20,6 +20,8 @@
  *
  */
 
+#if defined(ARDUINO_ARCH_STM32) && !defined(STM32GENERIC)
+
 #include "MarlinSPI.h"
 
 static void spi_init(spi_t *obj, uint32_t speed, spi_mode_e mode, uint8_t msb, uint32_t dataSize) {
@@ -159,3 +161,5 @@ uint8_t MarlinSPI::dmaSend(const void * transmitBuf, uint16_t length, bool minc)
   HAL_DMA_DeInit(&_dmaTx);
   return 1;
 }
+
+#endif // ARDUINO_ARCH_STM32 && !STM32GENERIC