libcamera: media_device: Open and close media device inside populate()

Remove the need for the caller to open and close the media device when
populating the MediaDevice. This is done as an effort to make the usage
of the MediaDevice less error prone and the interface stricter.

The rework also revealed and fixes a potential memory leak in
MediaDevice::populate() where resources would not be deleted if the
second MEDIA_IOC_G_TOPOLOGY would fail.

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

test/pipeline/ipu3/ipu3_pipeline_test.cpp

@@ -71,11 +71,6 @@ int IPU3PipelineTest::init()
 		return TestSkip;
 	}
 
-	if (cio2->open()) {
-		cerr << "Failed to open media device " << cio2->deviceNode() << endl;
-		return TestFail;
-	}
-
 	/*
 	 * Camera sensor are connected to the CIO2 unit.
 	 * Count how many sensors are connected in the system