MFC: r273546

Fix a bug where some DTS layouts could cause the premature ending of the
search (i.e. without returning any result) and you would end up with a
random MAC address.

Change the search algorithm to a recursive one to ensure that all the nodes
on DTS will be verified.

The previous algorithm could not keep up if the DTS has too many sub-nodes.

While here, fix the punctuation on comments.