dib0700: fix NULL-deref at probe

commit d5823511c0f8719a39e72ede1bce65411ac653b7 upstream.

Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer should a malicious device lack endpoints.

Fixes: c4018fa2 ("[media] dib0700: fix RC support on Hauppauge
Nova-TD")

Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>