thermal: intel: intel_pch: Improve cooling log

The intel_pch_thermal cooling mechanism currently only provides one of
the following final conclusions:
1. intel_pch_thermal 0000:00:12.0: CPU-PCH is cool [48C]
2. intel_pch_thermal 0000:00:12.0: CPU-PCH is cool [49C] after 30700 ms delay
3. intel_pch_thermal 0000:00:12.0: CPU-PCH is hot [60C] after 60000 ms delay. S0ix might fail
4. intel_pch_thermal 0000:00:12.0: Wakeup event detected, abort cooling

This does not provide sufficient context about what is happening,
especially for case 4.

Add one line log to indicate when PCH overheats and the cooling delay
has started.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>