IB/SA: Modify SA to implicitly cache Class Port info

SA will query and cache class port info as part of
its initialization. SA will also invalidate and
refresh the cache based on specific events. Callers such
as IPoIB and CM can query the SA to get the classportinfo
information. Apart from making the caller code much simpler,
this change puts the onus on the SA to query and maintain
classportinfo much like how it maitains the address handle to the SM.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Don Hiatt <don.hiatt@intel.com>
Signed-off-by: Dasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>