power: ltc4296: add driver & appplication

[amiclaus]

Pull Request Description

The LTC4296-1 is an IEEE 802.3cg-compliant, five port, single-pair power over Ethernet (SPoE), power sourcing equipment (PSE) controller. SPoE simplifies system design and installation with standardized power and Ethernet data over a single-pair cable. The LTC4296-1 is designed for interoperability with 802.3cg powered devices (PDs) in 24 V or 54 V systems.

PR Type

• [ ] Bug fix (change that fixes an issue)
• [x] New feature (change that adds new functionality)
• [ ] Breaking change (has dependencies in other repos or will cause CI to fail)

PR Checklist

• [x] I have followed the Coding style guidelines
• [x] I have performed a self-review of the changes
• [ ] I have commented my code, at least hard-to-understand parts
• [x] I have build all projects affected by the changes in this PR
• [ ] I have tested in hardware affected projects, at the relevant boards
• [x] I have signed off all commits from this PR
• [x] I have updated the documentation (wiki pages, ReadMe etc), if applies