AP_HAL_ESP32: add get_storage_ptr method

libraries/AP_HAL_ESP32/Storage.cpp

@@ -215,3 +215,16 @@ bool Storage::healthy(void)
 #endif
     return _initialised && AP_HAL::millis() - _last_empty_ms < 2000;
 }
+
+/*
+  get storage size and ptr
+ */
+bool Storage::get_storage_ptr(void *&ptr, size_t &size)
+{
+    if (!_initialised) {
+        return false;
+    }
+    ptr = _buffer;
+    size = sizeof(_buffer);
+    return true;
+}

libraries/AP_HAL_ESP32/Storage.h

@@ -39,6 +39,7 @@ public:
 
     void _timer_tick(void) override;
     bool healthy(void) override;
+    bool get_storage_ptr(void *&ptr, size_t &size) override;
 
 private:
     volatile bool _initialised;