eeepc-laptop: re-add check for eeepc->backlight == NULL

As Corentin points out, we do not create a backlight device if the ACPI
video driver is able to provide equivalent functionality. So we do need
to check before we try to update the backlight device.

We now ignore brightness events completely if we have not created a
backlight device.  This is slightly more cautious than the original
check.
Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/platform/x86/eeepc-laptop.c

@@ -1230,13 +1230,17 @@ static void eeepc_acpi_notify(struct acpi_device *device, u32 event)
 					dev_name(&device->dev), event,
 					count);
 
+	/* Brightness events are special */
 	if (event >= NOTIFY_BRN_MIN && event <= NOTIFY_BRN_MAX) {
+
+		/* Ignore them completely if the acpi video driver is used */
+		if (eeepc->backlight_device != NULL) {
 			int old_brightness, new_brightness;
 
-		/* Update backlight device. */
+			/* Update the backlight device. */
 			old_brightness = eeepc_backlight_notify(eeepc);
 
-		/* Convert brightness event to keypress (obsolescent hack). */
+			/* Convert event to keypress (obsolescent hack) */
 			new_brightness = event - NOTIFY_BRN_MIN;
 
 			if (new_brightness < old_brightness) {
@@ -1246,11 +1250,15 @@ static void eeepc_acpi_notify(struct acpi_device *device, u32 event)
 			} else {
 				/*
 				* no change in brightness - already at min/max,
-			 * event will be desired value (or else ignored).
+				* event will be desired value (or else ignored)
 				*/
 			}
+			eeepc_input_notify(eeepc, event);
 		}
+	} else {
+		/* Everything else is a bona-fide keypress event */
 		eeepc_input_notify(eeepc, event);
+	}
 }
 
 static void cmsg_quirk(struct eeepc_laptop *eeepc, int cm, const char *name)