HID: wacom: fix build breakage without CONFIG_LEDS_CLASS

CONFIG_HID_WACOM must depend on CONFIG_LEDS_CLASS, otherwise
CONFIG_NEW_LEDS may be disabled.

Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>