Input: wacom - remove unused bamboo HID parsing

Bamboo's do not declared a Digitizer-Stylus so the if() was
never executed.  wacom_features already contains correct stylus
packet length.

Signed-off-by: Chris Bagwell <chris@cnpbagwell.com>
Acked-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>