libcamera: device_enumerator: Constify argument to search function

The DeviceEnumerator::search() function doesn't need to modify its
DeviceMatch argument, make it const.

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

src/libcamera/include/device_enumerator.h

@@ -41,7 +41,7 @@ public:
 	virtual int init() = 0;
 	virtual int enumerate() = 0;
 
-	MediaDevice *search(DeviceMatch &dm) const;
+	MediaDevice *search(const DeviceMatch &dm) const;
 
 protected:
 	int addDevice(const std::string &devnode);