The relations between enum values and array indices values are currently
not enforced by the code, which makes them fragile w.r.t. future
changes.

Fix this by:
  1. Using designated array initializers, to make sure array indices and
     enums values match,
  2. Linking max9611_csa_gain enum values to the corresponding
     max9611_conf_ids enum values, as the latter is cast to the former
     in max9611_read_csa_voltage().

No change in generated code.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Acked-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>