device: redefine devicetree device definition using a more generic API

For devices defined using devicetree nodes we need to pass the
devicetree node, and to infer names for the device and the driver from
it.  Devices defined in the classical way don't need this.  Introduce
another level of private abstraction that accepts the information from
either source, falling back to the old parameters when the provided
node is invalid.

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>