V4L/DVB: cx23885: Return -ENXIO on slave nack

Documentation/i2c/fault-codes says that i2c adapter drivers should
return -ENXIO when no slave acks an address byte.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>