[media] cx88: fix error return code in cx8802_dvb_probe()

Fix to return error code -ENODEV from the error handling case
instead of 0(err maybe overwrited to 0 in the for loop), as
done elsewhere in this function.

[mchehab@s-opensource.com: remove a now uneeded set for err = -ENODEV]

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>