RDMA: Constify netdev->dev_addr accesses

mainline inclusion
from mainline-v5.15-rc5
commit fd92213e
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4QOTS
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/commit/?id=fd92213e9af3b8e5cb3b4d3bf925c9baafb46c9e

---------------------------------------------------------------------

netdev->dev_addr will become const soon, make sure drivers propagate the
qualifier.

Link: https://lore.kernel.org/r/20211019182604.1441387-4-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Acked-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
sigend-off-by: Guofeng Yue <yueguofeng@hisilicon.com>

Reviewed-by: Yangyang Li <liyangyang20@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>