media: pulse8-cec: persistent_config should be off by default

The persistent_config option is used to make the CEC settings persistent by using
the eeprom inside the device to store this information. This was on by default, which
caused confusion since this device now behaves differently from other CEC devices
which all come up unconfigured.

Another reason for doing this now is that I hope a more standard way of selecting
persistent configuration will be created in the future. And for that to work all
CEC drivers should behave the same and come up unconfigured by default.

None of the open source CEC applications are using this CEC framework at the moment
so change this behavior before it is too late.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: <stable@vger.kernel.org>      # for v4.10 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>