ACPI: thinkpad-acpi: make sure DSDT TMPx readings don't return +128

We get +128 instead of -128 from the DSDT TMPx methods, due to errors when
converting a EC byte return that is a s8 to an ACPI handler return that is
an int.

Fix it once and for all, by clamping acceptable temperature readings from
DSDT TMPx so that anything outside the [-127,+127] range is converted to
TP_EC_THERMAL_TMP_NA (-128).
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Michael Olbrich <michael.olbrich@gmx.net>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/misc/thinkpad_acpi.c

@@ -2853,6 +2853,8 @@ static int thermal_get_sensor(int idx, s32 *value)
 			snprintf(tmpi, sizeof(tmpi), "TMP%c", '0' + idx);
 			if (!acpi_evalf(ec_handle, &t, tmpi, "d"))
 				return -EIO;
+			if (t > 127 || t < -127)
+				t = TP_EC_THERMAL_TMP_NA;
 			*value = t * 1000;
 			return 0;
 		}