IB/sa: Add cached attribute containing SM information to SA port

Added a new SA port attribute containing SM ClassPortInfo fields,
(ClassPortInfo fields: Table 126 IB Spec 1.3.). This is useful for
checking SM support for specific features. The attribute is cached
to avoid resending queries, caching is done when a successful
ClassPortInfo reply is received on the port. Invalidation of the
attribute is done on SM change events, SM re-registration events,
and SM LID change events. The fields in ClassPortInfo should not
change during SM runtime without an event.

Signed-off-by: Alex Vesker <valex@mellanox.com>
Reviewed by: Hal Rosenstock <hal@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>