mlxsw: core: Extend devlink health reporter with new events and parameters

Extend the devlink health reporter registered by mlxsw to report new
health events and their related parameters. These are meant to aid in
debugging of hardware / firmware issues.

Beside the test event ('MLXSW_REG_MFDE_EVENT_ID_TEST') that is triggered
following the devlink health 'test' sub-command, the new events are used
to report the triggering of asserts in firmware code
('MLXSW_REG_MFDE_EVENT_ID_FW_ASSERT') and hardware issues
('MLXSW_REG_MFDE_EVENT_ID_FATAL_CAUSE').

Each event is accompanied with a severity parameter and per-event
parameters that are meant to help root cause the detected issue.

Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>