IB/mad: Eliminate redundant SM class version defines for OPA

and rename class version define to indicate SM rather than SMP or SMI

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>