net/mlx5: E-switch, Devcom, sync devcom events and devcom comp register

[ Upstream commit 8c253dfc ]

devcom events are sent to all registered component. Following the
cited patch, it is possible for two components, e.g.: two eswitches,
to send devcom events, while both components are registered. This
means eswitch layer will do double un/pairing, which is double
allocation and free of resources, even though only one un/pairing is
needed. flow example:

	cpu0					cpu1
	----					----

 mlx5_devlink_eswitch_mode_set(dev0)
  esw_offloads_devcom_init()
   mlx5_devcom_register_component(esw0)
                                         mlx5_devlink_eswitch_mode_set(dev1)
                                          esw_offloads_devcom_init()
                                           mlx5_devcom_register_component(esw1)
                                           mlx5_devcom_send_event()
   mlx5_devcom_send_event()

Hence, check whether the eswitches are already un/paired before
free/allocation of resources.

Fixes: 09b27846

 ("net: devlink: enable parallel ops on netlink interface")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>