Clean up W25QXXFlash class

Marlin/src/libs/W25Qxx.cpp

@@ -24,9 +24,10 @@
 
 #if HAS_SPI_FLASH
 
+#include "W25Qxx.h"
 #include <SPI.h>
 
-#include "W25Qxx.h"
+W25QXXFlash W25QXX;
 
 #ifndef SPI_FLASH_MISO_PIN
   #define SPI_FLASH_MISO_PIN W25QXX_MISO_PIN

Marlin/src/libs/W25Qxx.h

@@ -1,4 +1,4 @@
-/**
+/**
  * Marlin 3D Printer Firmware
  * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
  *
@@ -21,10 +21,6 @@
  */
 #pragma once
 
-//#ifdef __cplusplus
-//extern "C" { /* C-declarations for C++ */
-//#endif
-
 #include <stdint.h>
 
 #define W25X_WriteEnable        0x06
@@ -71,6 +67,4 @@ public:
   static void SPI_FLASH_BufferRead(uint8_t* pBuffer, uint32_t ReadAddr, uint16_t NumByteToRead);
 };
 
-//#ifdef __cplusplus
-//} /* C-declarations for C++ */
-//#endif
+extern W25QXXFlash W25QXX;