platform: x86: Deletion of checks before backlight_device_unregister()

The backlight_device_unregister() function tests whether its argument is NULL
and then returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
For msi-wmi.c:
Acked-by: Anisse Astier <anisse@astier.eu>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 21fc932..7543a56 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -1308,8 +1308,7 @@
 
 static void asus_wmi_backlight_exit(struct asus_wmi *asus)
 {
-	if (asus->backlight_device)
-		backlight_device_unregister(asus->backlight_device);
+	backlight_device_unregister(asus->backlight_device);
 
 	asus->backlight_device = NULL;
 }