This is a more flexible approach than adding a model flag and the C code to
just call libevdev_disable_event_code(). There's a risk users will think this
is is a configuration API but there are some devices out there (e.g. the
Microsoft Sculpt mouse) that need a more generic solution.

Case in point: the Sculpt mouse insists on holding BTN_SIDE down at all times.
We cannot ship any quirks for that device because we only have the receiver's
generic VID/PID. So a local override is required, but we might as well make
that one generic enough to catch other devices too in the future.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>