[media] cx231xx-cards: fix NULL-deref at probe

[media] cx231xx-cards: fix NULL-deref at probe

[ Upstream commit 0cd273bb5e4d1828efaaa8dfd11b7928131ed149 ]

Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer or accessing memory beyond the endpoint array should a
malicious device lack the expected endpoints.

Fixes: e0d3bafd0258 ("V4L/DVB (10954): Add cx231xx USB driver")
Cc: stable <stable@vger.kernel.org>     # 2.6.30
Cc: Sri Deevi <Srinivasa.Deevi@conexant.com>
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: Sasha Levin <alexander.levin@verizon.com>