Dev/ltm4681 add LTM4681 and LTM4682

[ivangilmercano]

The LTM4681 is a quad 31.25A or single 125A stepdown μModule® (power module) DC/DC regulator featuring remote configurability and telemetry-monitoring of power management parameters over PMBus. While, LTM®4682 is a quad 31.25A or single 125A step-down power μModule® (power micromodule) DC/DC regulator featuring remote configurability and telemetry monitoring of power management parameters over PMBus.

PR Description

• Commit 1 adds LTM4681 and LTM4682 to the dt-bindings of the existing LTC2978 driver
• Commit 2 adds LTM4681 and LTM4682 driver support on the existing LTC2978 driver
• Datasheets LTM4681, LTM4682

PR Type

• Bug fix (a change that fixes an issue)
• New feature (a change that adds new functionality)
• Breaking change (a change that affects other repos or cause CIs to fail)

PR Checklist

• I have conducted a self-review of my own code changes
• I have compiled my changes, including the documentation
• I have tested the changes on the relevant hardware
• I have updated the documentation outside this repo accordingly
• I have provided links for the relevant upstream lore