regulator: da9121: automotive variants identity fix

This patch fixes identification of DA913x parts by the DA9121 driver,
where a lack of clarity lead to implementation on the basis that variant
IDs were to be identical to the equivalent rated non-automotive parts.

There is a new emphasis on the DT identity to cope with overlap in these
ID's - this is not considered to be problematic, because projects would
be exclusively using automotive or consumer grade parts.

Signed-off-by: Adam Ward <Adam.Ward.opensource@diasemi.com>
Link: https://lore.kernel.org/r/20210421120306.DB5B880007F@slsrvapps-01.diasemi.com
Signed-off-by: Mark Brown <broonie@kernel.org>