infiniband: fix ulp/opa_vnic/opa_vnic_internal.h kernel-doc notation

Remove kernel-doc notation on 4 structs since they are internal and
none of the struct fields/members are described.
This removes 45 kernel-doc warnings.

Link: https://lore.kernel.org/r/20191010035239.818405496@gmail.com


Signed-off-by: Randy Dunlap <rd.dunlab@gmail.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>