IB/ehca: Notify consumers of LID/PKEY/SM changes after nondisruptive events

When firmware reports a nondisruptive port configuration change event,
previous versions of the eHCA driver didn't forward the event to consumers
like IPoIB.  Add code that determines the type of configuration change by
comparing old and new port attributes and reports it.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>