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/android/camera_ops.cpp

@@ -61,11 +61,12 @@ static int hal_dev_process_capture_request(const struct camera3_device *dev,
 	return camera->processCaptureRequest(request);
 }
 
-static void hal_dev_dump(const struct camera3_device *dev, int fd)
+static void hal_dev_dump([[maybe_unused]] const struct camera3_device *dev,
+			 [[maybe_unused]] int fd)
 {
 }
 
-static int hal_dev_flush(const struct camera3_device *dev)
+static int hal_dev_flush([[maybe_unused]] const struct camera3_device *dev)
 {
 	return 0;
 }