RDMA/hw/hfi1/mad: Demote half-completed kernel-doc header fix another

RDMA/hw/hfi1/mad: Demote half-completed kernel-doc header fix another

Fixes the following W=1 kernel build warning(s):

 drivers/infiniband/hw/hfi1/mad.c:1354: warning: Function parameter or member 'am' not described in '__subn_set_opa_portinfo'
 drivers/infiniband/hw/hfi1/mad.c:1354: warning: Function parameter or member 'data' not described in '__subn_set_opa_portinfo'
 drivers/infiniband/hw/hfi1/mad.c:1354: warning: Function parameter or member 'resp_len' not described in '__subn_set_opa_portinfo'
 drivers/infiniband/hw/hfi1/mad.c:1354: warning: Function parameter or member 'max_len' not described in '__subn_set_opa_portinfo'
 drivers/infiniband/hw/hfi1/mad.c:1354: warning: Function parameter or member 'local_mad' not described in '__subn_set_opa_portinfo'
 drivers/infiniband/hw/hfi1/mad.c:4919: warning: Function parameter or member 'out_mad_size' not described in 'hfi1_process_mad'
 drivers/infiniband/hw/hfi1/mad.c:4919: warning: Function parameter or member 'out_mad_pkey_index' not described in 'hfi1_process_mad'

Link: https://lore.kernel.org/r/20210126124732.3320971-5-lee.jones@linaro.org
Cc: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>