power_supply: add scope properties to some self-powered HID devices

The Wacom and Wiimote HID drivers register power supplies for themselves
to indicate their battery levels.  Make those power supplies device scope.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-wiimote.c b/drivers/hid/hid-wiimote.c
index 76739c0..98e4828 100644
--- a/drivers/hid/hid-wiimote.c
+++ b/drivers/hid/hid-wiimote.c
@@ -136,7 +136,8 @@
 };
 
 static enum power_supply_property wiimote_battery_props[] = {
-	POWER_SUPPLY_PROP_CAPACITY
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_SCOPE,
 };
 
 /* requires the state.lock spinlock to be held */
@@ -468,6 +469,11 @@
 	int ret = 0, state;
 	unsigned long flags;
 
+	if (psp == POWER_SUPPLY_PROP_SCOPE) {
+		val->intval = POWER_SUPPLY_SCOPE_DEVICE;
+		return 0;
+	}
+
 	ret = wiimote_cmd_acquire(wdata);
 	if (ret)
 		return ret;