google/panther: Be safe about invalid thermal readings

In case we get an invalid thermal reading, let's run the fan
at full speed rather than at low speed. This might impact the
user experiance slightly in cases where the bad reading does
not happen while the system is hot, but it will increase stability
in the cases where the system is actually overheating.

Also, set the critical temperature below tjmax, because otherwise
thermal shutdown by the OS will never be triggered.

Signed-off-by: Stefan Reinauer <reinauer@google.com>

BUG=chrome-os-partner:26045
BRANCH=panther, all haswell designs with ITE superIO
TEST=Unable to reproduce bug described in 26045

Change-Id: Iab262f1f17a5dff875c596d9e8d50e4e50ee90f9
Reviewed-on: https://chromium-review.googlesource.com/188556
Reviewed-by: Shawn Nematbakhsh <shawnn@chromium.org>
Commit-Queue: Stefan Reinauer <reinauer@chromium.org>
Tested-by: Stefan Reinauer <reinauer@chromium.org>

src/mainboard/google/panther/acpi/thermal.asl

@@ -76,12 +76,12 @@ Scope (\_TZ)
 
 			// Check for "no reading available
 			If (LEqual (Local0, 0x80)) {
-				Return (CTOK (\F2ON))
+				Return (CTOK (\F0ON))
 			}
 
 			// Check for invalid readings
 			If (LOr (LEqual (Local0, 255), LEqual (Local0, 0))) {
-				Return (CTOK (\F2ON))
+				Return (CTOK (\F0ON))
 			}
 
 			// PECI raw value is an offset from Tj_max

src/mainboard/google/panther/thermal.h

@@ -46,7 +46,7 @@
 #define FAN0_PWM		0xff
 
 /* Temperature which OS will shutdown at */
-#define CRITICAL_TEMPERATURE	100
+#define CRITICAL_TEMPERATURE	98
 
 /* Temperature which OS will throttle CPU */
 #define PASSIVE_TEMPERATURE	90