thermal: int340x: fix sparse warning

this patch fixes following sparse warning:

processor_thermal_device.c:188:6: warning: symbol 'proc_thermal_remove' was not declared. Should it be static?

Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/int340x_thermal/processor_thermal_device.c

@@ -274,7 +274,7 @@ free_buffer:
 	return ret;
 }
 
-void proc_thermal_remove(struct proc_thermal_device *proc_priv)
+static void proc_thermal_remove(struct proc_thermal_device *proc_priv)
 {
 	int340x_thermal_zone_remove(proc_priv->int340x_zone);
 	sysfs_remove_group(&proc_priv->dev->kobj,