regulator: da9062: refactor buck modes into header

This patch refactors buck modes into a header file so that device trees
can make use of these mode constants.

The new header filename uses da9063 because DA9063 was the earlier chip
and its driver code will want updating at some point in a similar manner.

Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
Link: https://lore.kernel.org/r/1573652416-9848-2-git-send-email-chf.fritz@googlemail.com


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