Reuse existing infrastructure to initialize and release DEVX uid.
The DevX interface is intended for user space access, so it is supposed
to be initialized before ib_register_device(). Also it isn't supported
in switchdev mode and don't need to initialize it in that mode.

Fixes: 76dc5a84 ("IB/mlx5: Manage device uid for DEVX white list commands")
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>