IB/cm: Add interim support for routed paths

Paths with hop_limit > 1 indicate that the connection will be routed
between IB subnets.  Update the subnet local field in the CM REQ based
on the hop_limit value.  In addition, if the path is routed, then set
the LIDs in the REQ to the permissive LIDs.  This is used to indicate
to the passive side that it should use the LIDs in the received local
route header (LRH) associated with the REQ when programming the QP.

This is a temporary work-around to the IB CM to support IB router
development until the IB router specification is completed.  It is not
anticipated that this work-around will cause any interoperability
issues with existing stacks or future stacks that will properly
support IB routers when defined.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>