Input: wacom - add basic Intuos5 support

This patch adds support for the basic pen functions of Intuos5
tablets.

Signed-off-by: Jason Gerecke <killertofu@gmail.com>
Reviewed-by: Chris Bagwell <chris@cnpbagwell.com>
Reviewed-by: Ping Cheng <pingc@wacom.com>
Tested-by: Timo Aaltonen <tjaalton@ubuntu.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>