regulator: bd9576: Constify the voltage tables

Also use unsigned int instead of int for the voltage tables.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20210525100405.2506483-1-axel.lin@ingics.com


Signed-off-by: Mark Brown <broonie@kernel.org>