net/mlx5: E-switch, store eswitch pointer before registering devlink_param

Next patch will move devlink register to be first. Therefore, whenever
mlx5 will register a param, the user will be notified.
In order to notify the user, devlink is using the get() callback of
the param. Hence, resources that are being used by the get() callback
must be set before the devlink param is registered.

Therefore, store eswitch pointer inside mdev before registering the
param.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20240409190820.227554-2-tariqt@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>