Revert "mlxsw: core: Add the hottest thermal zone detection"

This reverts commit 2dc2f760 and
commit 6f73862f.

As discussed in the thread:

https://lore.kernel.org/all/f3c62ebe-7d59-c537-a010-bff366c8aeba@linaro.org/

the feature provided by commits 2dc2f760 and 6f73862f is
actually already handled by the thermal framework via the cooling
device state aggregation, thus all this code is pointless.

The revert conflicts with the following changes:
 - 7f4957be: thermal: Use mode helpers in drivers
 - 6a79507c: mlxsw: core: Extend thermal module with per QSFP module thermal zones

These conflicts were fixed and the resulting changes are in this patch.

Both reverts are in the same change as requested by Ido Schimmel:

https://lore.kernel.org/all/Yvz7+RUsmVco3Xpj@shredder/



Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Tested-by: Vadim Pasternak <vadimp@nvidia.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/20220817153040.2464245-1-daniel.lezcano@linaro.org