libcamera: software_isp: Clear pending async work

Debayering is carried out on `ispWorkerThread_`. When stopping, the queued
work needs to be flushed or cancelled to ensure that the next time it starts,
it won't process stale data. So remove all messages targeting the `Debayer`
object on the worker thread.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Tested-by: Robert Mader <robert.mader@collabora.com>

src/libcamera/software_isp/software_isp.cpp

@@ -358,6 +358,7 @@ void SoftwareIsp::stop()
 {
 	ispWorkerThread_.exit();
 	ispWorkerThread_.wait();
+	ispWorkerThread_.removeMessages(debayer_.get());
 
 	Thread::current()->dispatchMessages(Message::Type::InvokeMessage, this);