HID: wacom: leds: dynamically allocate LED groups

We need to add an action to ensure wacom->led.groups is null when
wacom_led_control() gets called after the resources has been freed.

This also prevents to send a LED command when there is no support
from the device.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 3e2c903..932d3ee 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -808,7 +808,7 @@
 
 	for (i = 0; i < WACOM_MAX_REMOTES; i++) {
 		if (wacom_wac->serial[i] == serial)
-			wacom->led.select[i] = touch_ring_mode;
+			wacom->led.groups[i].select = touch_ring_mode;
 	}
 
 	if (!wacom->battery &&