Input: wacom - put a flag when the led are initialized

This solves a bug with the wireless receiver:
- at plug, the wireless receiver does not know which Wacom device it is
  connected to, so it does not actually creates all the LEDs
- when the tablet connects, wacom->wacom_wac.features.type is set to the
  proper device so that wacom_wac can understand the packets
- when the receiver is unplugged, it detects that a LED should have been
  created (based on wacom->wacom_wac.features.type) and tries to remove
  it: crash when removing the sysfs group.

Side effect, we can now safely call several times wacom_destroy_leds().
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/hid/wacom.h

@@ -118,6 +118,7 @@ struct wacom {
 		u8 hlv;       /* status led brightness button pressed (1..127) */
 		u8 img_lum;   /* OLED matrix display brightness */
 	} led;
+	bool led_initialized;
 	struct power_supply battery;
 };
 

drivers/hid/wacom_sys.c

@@ -729,12 +729,18 @@ static int wacom_initialize_leds(struct wacom *wacom)
 		return error;
 	}
 	wacom_led_control(wacom);
+	wacom->led_initialized = true;
 
 	return 0;
 }
 
 static void wacom_destroy_leds(struct wacom *wacom)
 {
+	if (!wacom->led_initialized)
+		return;
+
+	wacom->led_initialized = false;
+
 	switch (wacom->wacom_wac.features.type) {
 	case INTUOS4S:
 	case INTUOS4: