thermal: int340x: Provide notification for OEM variable change

When we receive ACPI notification for OEM variable change pass the
notification to user space handler. This will avoid polling for
OEM variable change from user space.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200915223650.406046-2-srinivas.pandruvada@linux.intel.com