Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer should a malicious device lack endpoints.
Fixes: c04148f915e5 ("Input: add driver for USB VoIP phones with CM109...") Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>