hw/sensor: add Maxim MAX31785 device

hw/sensor: add Maxim MAX31785 device

MAX31785 is a PMBus compliant 6-Channel fan controller. It supports 6 fan
channels, 11 temperature sensors, and 6-Channel ADC to measure the remote
voltages. Datasheet can be found here:
https://datasheets.maximintegrated.com/en/ds/MAX31785.pdf

This initial version of the driver has skeleton and support for the
fan channels. Requests for temperature sensors, and ADC Channels the
are serviced with the default values as per the datasheet.  No additional
instrumentation is done. NV Log feature is not supported.

Signed-off-by: Maheswara Kurapati <quic_mkurapat@quicinc.com>
Signed-off-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20220627154703.148943-5-quic_jaehyoo@quicinc.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>