thermal: intel: Fix unsigned comparison with less than zero

The return value from the call to intel_tcc_get_tjmax() is int, which can
be a negative error code. However, the return value is being assigned to
an u32 variable 'tj_max', so making 'tj_max' an int.

Eliminate the following warning:
./drivers/thermal/intel/intel_soc_dts_iosf.c:394:5-11: WARNING: Unsigned expression compared with zero: tj_max < 0

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=3637Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/thermal/intel/intel_soc_dts_iosf.c

@@ -380,7 +380,7 @@ struct intel_soc_dts_sensors *intel_soc_dts_iosf_init(
 {
 	struct intel_soc_dts_sensors *sensors;
 	bool notification;
-	u32 tj_max;
+	int tj_max;
 	int ret;
 	int i;