This change creates a second input device which will handle input from
a Surface Pen. The Surface Pen supplies a different packet header than
touch events, so it is simple to handle one or the other.

This patch handles both the newer Surface Pen with one button, and the
older variant with a second button to switch to Eraser mode.
Signed-off-by: NStephen Just <stephenjust@gmail.com>
Reviewed-and-tested-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

Surface Pens can be supported by handling a second report type. Prepare
for this change.
Signed-off-by: NStephen Just <stephenjust@gmail.com>
Reviewed-and-tested-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

This is a basic driver for the Surface 3. I am not so sure it will work
with any firmwares as most values are encoded, but given that I only have
access to my current device with its firmware and I don't have the
datasheet, it should be OK for now.

The Surface Pen is not supported (if it is supposed to be). I'll work on
this when I get one.
Tested-by: NBastien Nocera <hadess@hadess.net>
Signed-off-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>