Check against the upper temperature limit (125 degrees C) before
consider the temperature valid.

Fixes: 5eed800a ("thermal: imx8mm: Add support for i.MX8MM thermal monitoring unit")
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Reviewed-by: Jacky Bai <ping.bai@nxp.com>
Link: https://lore.kernel.org/r/20221014073507.1594844-1-marcus.folkesson@gmail.comSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>