Thermal/step_wise: Fix that hysteresis takes no effect

Test command

  nsh> cat /proc/thermal/cpu-thermal

Trips

  /* Copy from drivers/thermal/thermal_dummy.c */

  {.name = "cpu_crit",   .temp = 90, .hyst = 5, .type = THERMAL_CRITICAL},
  {.name = "cpu_alert1", .temp = 70, .hyst = 5, .type = THERMAL_HOT},
  {.name = "cpu_alert0", .temp = 60, .hyst = 5, .type = THERMAL_NORMAL},

Without this patch

  # Error occured when temperature jump to 69.

  z:cpu-thermal t:67 t:1 h:16 l:0 c:fan0 s:0|(invalid)
  z:cpu-thermal t:72 t:1 h:16 l:0 c:fan0 s:1|1
  z:cpu-thermal t:69 t:1 h:16 l:0 c:fan0 s:0|0
  z:cpu-thermal t:74 t:1 h:16 l:0 c:fan0 s:1|1

With this patch

  z:cpu-thermal t:67 t:1 h:16 l:0 c:fan0 s:0|(invalid)
  z:cpu-thermal t:72 t:1 h:16 l:0 c:fan0 s:1|1
  z:cpu-thermal t:69 t:1 h:16 l:0 c:fan0 s:1|1
  z:cpu-thermal t:74 t:1 h:16 l:0 c:fan0 s:2|2

Signed-off-by: wangjianyu3 <wangjianyu3@xiaomi.com>

Author: JianyuWang0623

drivers/thermal/thermal_step_wise.c

@@ -152,8 +152,10 @@ static int step_wise_throttle(FAR struct thermal_zone_device_s *zdev,
   enum thermal_trend_e trend;
   unsigned int next_state;
   bool throttle = false;
+  int hyst_temp;
   int trip_temp;
 
+  thermal_zone_get_trip_hyst(zdev, trip, &hyst_temp);
   thermal_zone_get_trip_temp(zdev, trip, &trip_temp);
 
   trend = thermal_zone_get_trend(zdev);
@@ -162,6 +164,10 @@ static int step_wise_throttle(FAR struct thermal_zone_device_s *zdev,
     {
       throttle = true;
     }
+  else if (zdev->temperature > trip_temp - hyst_temp)
+    {
+      return OK;
+    }
 
   list_for_every_entry(&zdev->instance_list, instance,
                        struct thermal_instance_s, zdev_node)