In the MT6358 regulator driver, each regulator is described by a
|struct regulator_desc| wrapped by a |struct mt6358_regulator_info|.
The latter was tied to the regulator device using the config's
driver_data field, which meant that the variables could not be constant.

Since each regulator device has a pointer to its regulator_desc, and
mt6358_regulator_info wraps that, the driver could use container_of()
to retrieve it instead.

Switch to using container_of(), drop tha driver_data setting, and
const-ify all the regulator descriptions.
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20230609083009.2822259-6-wenst@chromium.orgSigned-off-by: Mark Brown <broonie@kernel.org>