hw/sensor: add ADM1266 device model

hw/sensor: add ADM1266 device model

The ADM1266 is a cascadable super sequencer with margin control and
fault recording.
This commit adds basic support for its PMBus commands and models
the identification registers that can be modified in a firmware
update.

Reviewed-by: Hao Wu <wuhaotsh@google.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Titus Rwantare <titusr@google.com>
[PMD: Cover file in MAINTAINERS]
Message-ID: <20231023-staging-pmbus-v3-v4-5-07a8cb7cd20a@google.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>