The vaux2 (VCSI) regulator is left on by the bootloader
in rx-51. Since there the product has shipped and there
won't be any bootloader updates to fix this issue, we
need to define all the regulators and declare full
constraints for the regulator FW. This will allow the
regulator FW to disable unused regulators.

Also this helps in adding more fine grain regulator
support for rx-51 in the future.

Thanks for Mark Brown for pointing out the correct
solution.
Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@nokia.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>