sys/v4l2/gstv4l2object.c: If "device-name" is requested and the device is not open, try to temporarily open it to obt...

Original commit message from CVS:
Patch by: Martin Szulecki
* sys/v4l2/gstv4l2object.c: (gst_v4l2_object_get_property_helper):
If "device-name" is requested and the device is not
open, try to temporarily open it to obtain this
information (#342494).