v4l2: v4l2_compat_manager: Print path and fd in openat()

The V4L2 compat layer prints debug messages that mention the file
descriptor of the video device, but no message that links the device
path to the file descriptor. Fix it by adding a debug message in
openat().

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

src/v4l2/v4l2_compat_manager.cpp

@@ -158,6 +158,7 @@ int V4L2CompatManager::openat(int dirfd, const char *path, int oflag, mode_t mod
 	V4L2CameraProxy *proxy = proxies_[ret].get();
 	files_.emplace(efd, std::make_shared<V4L2CameraFile>(efd, oflag & O_NONBLOCK, proxy));
 
+	LOG(V4L2Compat, Debug) << "Opened " << path << " -> fd " << efd;
 	return efd;
 }