Input: wacom - wireless monitor framework

The 3rd gen Bamboo Pen & Touch and Intuos5 tablets support an
optional wireless module. When its receiver is plugged into USB,
it presents 3 interfaces: 0) Monitor 1) Pen and 2) Touch.

The exact capabilities of the Pen and Touch interfaces can
not be determined until a tablet connection is established
and reported over the Monitor interface.

This patch detects this wireless receiver and enables interrupt
packets to be processed for the Monitor interface. Processing
the data in packets will be left to another patch.

Since it doesn't make sense to create an input device for the
Monitor interface, it is not created. Creation of Pen and Touch
input device is also delayed until monitor packets can be processed.

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