android: camera_metadata: Add const version of get()

Add a const version of the CameraMetadata::get() method to retrieve
a const pointer to the camera metadata wrapped by the class instance.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/android/camera_metadata.cpp

@@ -50,3 +50,8 @@ camera_metadata_t *CameraMetadata::get()
 {
 	return valid_ ? metadata_ : nullptr;
 }
+
+const camera_metadata_t *CameraMetadata::get() const
+{
+	return valid_ ? metadata_ : nullptr;
+}

src/android/camera_metadata.h

@@ -21,6 +21,7 @@ public:
 	bool addEntry(uint32_t tag, const void *data, size_t data_count);
 
 	camera_metadata_t *get();
+	const camera_metadata_t *get() const;
 
 private:
 	camera_metadata_t *metadata_;