net/mlx5: Notify on trap action by blocking event

In order to allow mlx5 core driver to trigger synchronous operations to
its consumers, add a blocking events handler. Add wrappers to
blocking_notifier_[call_chain/chain_register/chain_unregister]. Add trap
callback for action set and notify about this change. Following patches
in the set add a listener for this event.

Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>