V4L/DVB (6465): Use correct error codes when chip is not recognized

If the chip isn't recognized, then the correct errors should be returned.
The v4l2_i2c_attach() utility function will return 0 for all errors
except -ENOMEM to provide proper compatibility support for the old I2C
probing function.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>