staging: gigaset: add endpoint-type sanity check

Add missing endpoint-type sanity checks to probe.

This specifically prevents a warning in USB core on URB submission when
fuzzing USB descriptors.

Signed-off-by: Johan Hovold <johan@kernel.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191202085610.12719-4-johan@kernel.org


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