thermal: intel: int340x: simplify the code with module_platform_driver()

The init/exit() of the driver only calls platform_driver_{un}register(),
so it can be simpilfied by using module_platform_driver().

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>