@brief Reserve a set of GPIO lines. @param bulk Set of GPIO lines to reserve. @param config Request options. @param default_vals Initial line values - only relevant if we're setting the direction to output. @return 0 if the all lines were properly requested. In case of an error this routine returns -1 and sets the last error number.
If this routine succeeds, the caller takes ownership of the GPIO lines until they're released. All the requested lines must be prodivided by the same gpiochip.