net/mlx5: Disallow SRIOV switchdev mode when in multi-PF netdev

Adaptations need to be made for the auxiliary device management in the
core driver level. Block this combination for now.

Fixes: 678eb448

 ("net/mlx5: SD, Implement basic query and instantiation")
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Link: https://lore.kernel.org/r/20240409190820.227554-12-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>