thermal/drivers/sti: Cleanup code related to stih416

"st,stih416-mpe-thermal" compatible seems to appear nowhere in the
device-tree nor in the documentation.
Remove compatible and related code.

Signed-off-by: Raphael Gallais-Pou <rgallaispou@gmail.com>
Link: https://lore.kernel.org/r/20240708161840.102004-1-rgallaispou@gmail.com


Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>