AP_HAL_Linux: add get_storage_ptr method

libraries/AP_HAL_Linux/Storage.cpp

@@ -266,3 +266,16 @@ void Storage::_timer_tick(void)
         }
     }
 }
+
+/*
+  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_Linux/Storage.h

@@ -32,6 +32,8 @@ public:
     void write_dword(uint16_t loc, uint32_t value);
     void write_block(uint16_t dst, const void* src, size_t n) override;
 
+    bool get_storage_ptr(void *&ptr, size_t &size) override;
+
     virtual void _timer_tick(void) override;
 
 protected: