meson: Remove -Wno-unused-parameter

We build libcamera with -Wno-unused-parameter and this doesn't cause
much issue internally. However, it prevents catching unused parameters
in inline functions defined in public headers. This can lead to
compilation warnings for applications compiled without
-Wno-unused-parameter.

To catch those issues, remove -Wno-unused-parameter and fix all the
related warnings with [[maybe_unused]].

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

src/libcamera/pipeline/raspberrypi/raspberrypi.cpp

@@ -758,7 +758,7 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
 	return ret;
 }
 
-int PipelineHandlerRPi::exportFrameBuffers(Camera *camera, Stream *stream,
+int PipelineHandlerRPi::exportFrameBuffers([[maybe_unused]] Camera *camera, Stream *stream,
 					   std::vector<std::unique_ptr<FrameBuffer>> *buffers)
 {
 	RPiStream *s = static_cast<RPiStream *>(stream);
@@ -1182,7 +1182,8 @@ int RPiCameraData::configureIPA()
 	return 0;
 }
 
-void RPiCameraData::queueFrameAction(unsigned int frame, const IPAOperationData &action)
+void RPiCameraData::queueFrameAction([[maybe_unused]] unsigned int frame,
+				     const IPAOperationData &action)
 {
 	/*
 	 * The following actions can be handled when the pipeline handler is in