staging: gdm724x: drop unused CDC defines

This driver has a copy of some of the CDC defines but which are
currently unused.

Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20220725075841.1187-6-johan@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>