Linux: net/mlx5e: Move representor vnic reporter to eswitch devlink port

In the Linux kernel, the following vulnerability has been resolved:

net/mlx5e: Move representor vnic reporter to eswitch devlink port

The representor vnic devlink health reporter is created and destroyed along the representor netdev (un)load path, which is not serialized by the devlink instance lock. Destroying the reporter from there triggers a devl_assert_locked() splat on driver unbind: WARNING: net/devlink/core.c:259 at devl_assert_locked+0x54/0x70, CPU#2: bash/3758 Modules linked in: mlx5_vdpa vringh vdpa mlx5_ib mlx5_fwctl mlx5_core ... CPU: 2 UID: 0 PID: 3758 Comm: bash Tainted: G W 6.19.0+ #1 PREEMPT Tainted: [W]=WARN Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), ... RIP: 0010:devl_assert_locked+0x54/0x70 Call Trace: <TASK> devl_health_reporter_destroy+0x3a/0x1b0 mlx5e_vport_rep_unload+0x12d/0x2b0 [mlx5_core] mlx5_eswitch_unregister_vport_reps+0x1b8/0x220 [mlx5_core] ? __esw_offloads_unload_rep+0x190/0x190 [mlx5_core] ? kernfs_remove_by_name_ns+0xc3/0xf0 device_release_driver_internal+0x3b2/0x560 unbind_store+0xce/0xf0

Move the reporter's lifecycle to the eswitch devlink port (un)register paths, which are already serialized by the devlink instance lock, and store the handle on mlx5_devlink_port. Use the port's mlx5_vport as the reporter priv since the diagnose callback only needs a device handle and a vport number, and mlx5_vport carries both and is initialized before any representor driver probes.