dt-bindings: google,cros-ec-keyb: Fixup bad compatible match

This uses anyOf which is wrong. Use oneOf and move the items under the
description. Also drop allOf for $ref.

Reported-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/CAE-0n50KE9bkqZvCOLtCGiq3g1jYhK7zpVcVFBzinaguNhNaPw@mail.gmail.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>