Input: wacom - replace WACOM_PKGLEN_PENABLED

Replacing WACOM_PKGLEN_PENABLED with WACOM_PKGLEN_GRAPHIRE since
they both represent the same value, 8. This value will be used
for both Tablet PC and Bamboo with touch devices.

Signed-off-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>