Add a standalone INA231 power monitor driver modeled after the existing
INA226 driver. The INA231 is register-compatible with the INA226 but
lacks manufacturer/die ID registers, so probe reads the config register
instead. Default parameter values (config, shunt, max current) are
aligned with the voxlpm driver's INA231 configuration.
Enable the driver on the voxl2 board and add INA231 support to the
voxl-px4-start script.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
