IB/core: Move SM class defines from ib_mad.h to ib_smi.h

When the hfi1 driver was added these definitions were moved from the qib driver
to ib_mad.h to be used by both qib and hfi1.  They should have been moved to
ib_smi.h instead.

Fixes: d4ab3470 ("IB/core: Add core header changes needed for OPA")
Reviewed-by: Hal Rosenstock <hal@mellanox.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>