libcamera: v4l2_videodevice: Add helper to queue all buffers

When starting the stream on a capture video device it is often needed to
queue all the allocated buffers. Add a helper method to do so, and
refactor the existing queueBuffer() method to make it clearer.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/include/v4l2_videodevice.h

@@ -139,6 +139,7 @@ public:
 	int releaseBuffers();
 
 	int queueBuffer(Buffer *buffer);
+	std::vector<std::unique_ptr<Buffer>> queueAllBuffers();
 	Signal<Buffer *> bufferReady;
 
 	int streamOn();