xivo-yealink-2015-03: set auto_provision.custom.protect for all models

Also homogenize a little some parameters between the differents models.
There is still work to be done there.

Note that regarding the auto_provision.custom.protect parameter, not all
models supports it; all phones in version earlier than V73 do not. This
includes:

* T32G
* T38G
* T19P
* T21P