RDMA/hns: Avoid filling sl in high 3 bits of vlan_id

Only the low 12 bits of vlan_id is valid, and service level has been
filled in Address Vector. So there is no need to fill sl in vlan_id in
Address Vector.

Fixes: 7406c003

 ("RDMA/hns: Only record vlan info for HIP08")
Link: https://lore.kernel.org/r/1607650657-35992-5-git-send-email-liweihang@huawei.com
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>