thermal/drivers/amlogic: Rename Uptat to uptat to follow kernel coding style

thermal/drivers/amlogic: Rename Uptat to uptat to follow kernel coding style

The variable Uptat uses CamelCase, which violates the kernel's coding
style that mandates snake_case for variable names. This is a purely
cosmetic change with no functional impact.

Compilation tested with:
- checkpatch.pl --strict passed (no new warnings/errors).

Signed-off-by: Enrique Isidoro Vazquez Ramos <kike.correo99.f@gmail.com>
Link: https://lore.kernel.org/r/Z-MEZNMLUmj75uxN@debian.debian
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>