Rely on list->outbuf rather on mVirtualonExtActive

* Rely on list->outbuf rather on mVirtualonExtActive
to determine a virtual display device

* This helps in cases where SSD/SR is started after
a non-Hybrid WFD session becomes active. We need
to update retireFenceFd of SSD/SR which used to not
happen since mVirtualonExtActive is set becomes of
an active non-Hybrid WFD session

Change-Id: Ib42af62e723b5f62f62a1a8d280f0c9af49683d7
1 file changed