ENGR00218810-2 [Thermal]Add thermal alarm function

ENGR00218810-2 [Thermal]Add thermal alarm function

1. Current thermal framework use delayed work to update
temperature, but delayed work may be blocked if system is
busy with the high priority task, which will cause the thermal
protect function not working in time, so we need to add alarm
function, when temperature reach the critical point, the alarm
function will generate an interrupt to reboot system.

2. No need to read 5 times of sensor value, read once is enough.

Signed-off-by: Anson Huang <b20788@freescale.com>