Add the following two APIs to Machine Description (MDESC)
- mdesc_get_node: Searches for a node in the Machine
  Description tree based on given information about
  that node.
- mdesc_get_node_info: Retrieves information about a
  given node.
Signed-off-by: NJagannathan Raman <jag.raman@oracle.com>
Reviewed-by: NLiam Merwick <liam.merwick@oracle.com>
Reviewed-by: NShannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>