libcamera: v4l2_videodevice: Add color space to format string representation

To debug color issues in a pipeline it is necessary to know the color
space used. Therefore add the color space to the string representation
of V4L2DeviceFormat that is returned by toString() and operator<<(). The
format gets for example printed as

[0:05:52.981684000] [230] DEBUG RkISP1 rkisp1_path.cpp:468 Configured main resizer video device with 1920x1080-NV12/sYCC

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <uajain@igalia.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/v4l2_videodevice.cpp

@@ -446,7 +446,8 @@ const std::string V4L2DeviceFormat::toString() const
  */
 std::ostream &operator<<(std::ostream &out, const V4L2DeviceFormat &f)
 {
-	out << f.size << "-" << f.fourcc;
+	out << f.size << "-" << f.fourcc << "/"
+	    << ColorSpace::toString(f.colorSpace);
 	return out;
 }