More Rust bindings for device property reads This adds more Rust bindings for reading device properties, based on Rob Herring's work. I'm working on a driver[1] that uses these, but the driver has more dependencies than this. Rob Herring and Dirk Behme did several review iterations over on Zulip already[1], I'm thankful for their great input. This is my first time posting to the mailing list, please let me know if I did anything wrong. Remo [1] https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/DS90UB954.20driver.20done.2C.20ready.20to.20upstream.3F/with/507874342
