netdevsim: Add devlink port resource registration

netdevsim: Add devlink port resource registration

Register port-level resources for netdevsim ports to enable testing
of the port resource infrastructure.

Signed-off-by: Or Har-Toov <ohartoov@nvidia.com>
Reviewed-by: Shay Drori <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260407194107.148063-5-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>