RDMA/mlx5: Use dev_addr_mod()

Commit 406f42fa ("net-next: When a bond have a massive amount of
VLANs...") introduced a rbtree for faster Ethernet address look up. To
maintain netdev->dev_addr in this tree we need to make all the writes to
it got through appropriate helpers.

Link: https://lore.kernel.org/r/20211019182604.1441387-3-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>