HID: wacom_sys: Demote kernel-doc abuse

Fixes the following W=1 kernel build warning(s):

drivers/hid/wacom_sys.c:1505: warning: Function parameter or member 'wacom' not described in 'wacom_led_next'
drivers/hid/wacom_sys.c:1505: warning: Function parameter or member 'cur' not described in 'wacom_led_next'

Cc: Jiri Kosina <[e-mail]>
Cc: Benjamin Tissoires <[e-mail]>
Cc: [e-mail]
Signed-off-by: Lee Jones <[e-mail]>
Signed-off-by: Benjamin Tissoires <[e-mail]>

drivers/hid/wacom_sys.c

···
 	return &group->leds[id];
 }
 
-/**
+/*
  * wacom_led_next: gives the next available led with a wacom trigger.
  *
  * returns the next available struct wacom_led which has its default trigger