fixup! drivers/mtd_default: use XFA with MTD pointers

drivers/include/mtd_default.h

@@ -25,6 +25,47 @@
 extern "C" {
 #endif
 
+#if defined(MODULE_MTD_SDCARD_DEFAULT)
+#include "mtd_sdcard.h"
+#endif
+
+#if defined(MODULE_MTD_EMULATED)
+#include "mtd_emulated.h"
+#endif
+
+#if !DOXYGEN
+
+/**
+ * @brief   Declare `mtd*` according to the `MTD_*` symbols defined by the board
+ */
+#ifdef MTD_0
+extern mtd_dev_t *MTD_0;
+#endif
+#ifdef MTD_1
+extern mtd_dev_t *MTD_1;
+#endif
+#ifdef MTD_2
+extern mtd_dev_t *MTD_2;
+#endif
+#ifdef MTD_3
+extern mtd_dev_t *MTD_3;
+#endif
+#ifdef MTD_4
+extern mtd_dev_t *MTD_4;
+#endif
+#ifdef MTD_5
+extern mtd_dev_t *MTD_5;
+#endif
+#endif /* !DOXYGEN */
+
+#if defined(MODULE_MTD_SDCARD_DEFAULT)
+extern mtd_sdcard_t mtd_sdcard_dev0;
+#endif
+
+#if defined(MODULE_MTD_EMULATED)
+extern mtd_emulated_t mtd_emulated_dev0;
+#endif
+
 /**
  * @brief   Get the default MTD device by index
  *