[DM/THERMAL] Fixup the C99, 6.8.1 Labeled statements p4

Append a null statement for "Any statement may be preceded by a prefix that declares an identifier as a label name."

Signed-off-by: GuEe-GUI <2991707448@qq.com>

components/drivers/thermal/thermal.c

@@ -223,6 +223,7 @@ _scan_cooling:
         }
     }
 _end:
+    ;
 }
 #else
 rt_inline void thermal_ofw_setup(struct rt_ofw_node *np, struct rt_thermal_zone_device *zdev)