mlxsw: thermal: Read module temperature thresholds using MTMP register

mlxsw_thermal_module_trips_update() is used to update the trip points of
the module's thermal zone. Currently, this is done by querying the
thresholds from the module's EEPROM via MCIA register. This data does
not pass validation and in some cases can be unreliable. For example,
due to some problem with transceiver module.

Previous patch made it possible to read module's temperature and
thresholds via MTMP register. Therefore, extend
mlxsw_thermal_module_trips_update() to use the thresholds queried from
MTMP, if valid.

This is both more reliable and more efficient than current method, as
temperature and thresholds are queried in one transaction instead of
three. This is significant when working over a slow bus such as I2C.

Signed-off-by: Mykola Kostenok <c_mykolak@nvidia.com>
Acked-by: Vadim Pasternak <vadimp@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>