This is similar to change I668643c836d46a25df46d4c99a973af5e50a39db
where the objects returned in a list from a libvirt call were not
tpool.Proxy wrapped. Because the objects are not wrapped, calling
methods on them such as listCaps() can block all other greenthreads
and can cause nova-compute to freeze for hours in certain scenarios.
This adds the same wrapping to libvirt calls which return lists of
virNodeDevice.
Closes-Bug: #2091033
Change-Id: I60d6f04d374e9ede5895a43b7a75e955b0fea3c5