RDMA/mlx5: Obtain upper net device only when needed

RDMA/mlx5: Obtain upper net device only when needed

Report the upper device's state as the RDMA port state only in RoCE LAG or
switchdev LAG.

Fixes: 27f9e0ccb6da ("net/mlx5: Lag, Add single RDMA device in multiport mode")
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Link: https://patch.msgid.link/20240909173025.30422-3-michaelgur@nvidia.com
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>