IB/mlx5: Support querying eswitch functions from DEVX

Query eswitch functions returns information of the external host
PF(if it exists). It can be used to check if DEVX is running on ECPF.

Reviewed-by: Erez Shitrit <erezsh@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Bodong Wang <bodong@mellanox.com>
Link: https://lore.kernel.org/r/4265925178ab3224dc1d3e3784bb312d808edca5.1661763785.git.leonro@nvidia.com


Signed-off-by: Leon Romanovsky <leon@kernel.org>