Add devicetree configuration and device variant parameters. Use the latter
to enable the check and use of parameters specific to dual buck variants.
Signed-off-by: NAdam Ward <Adam.Ward.opensource@diasemi.com>
Link: https://lore.kernel.org/r/5849ce60595aef1018bdde7dcfb54a7397597545.1606755367.git.Adam.Ward.opensource@diasemi.comSigned-off-by: NMark Brown <broonie@kernel.org>