Add support for the Monolithic Power Systems MPM3695 family.
It contains four devices with suffixes: -10, -20, -25 and -100.
The device is PMBus compliant and shares characteristics with the
MPM82504.
MPM3695-25 has different VOLTAGE_SCALE_LOOP register size [11:0]
and it needs to be separated because it will be configured in the next
commit.