libcamera: Add pointer to MediaDevice to MediaObject

Add a MediaDevice member field to the MediaObject class hierarcy.
Each media object now has a reference to the media device it belongs to,
and which it has been created by.

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

src/libcamera/media_device.cpp

@@ -430,11 +430,11 @@ bool MediaDevice::populateEntities(const struct media_v2_topology &topology)
 
 		MediaEntity *entity;
 		if (iface)
-			entity = new MediaEntity(&mediaEntities[i],
+			entity = new MediaEntity(this, &mediaEntities[i],
 						 iface->devnode.major,
 						 iface->devnode.minor);
 		else
-			entity = new MediaEntity(&mediaEntities[i]);
+			entity = new MediaEntity(this, &mediaEntities[i]);
 
 		if (!addObject(entity)) {
 			delete entity;