regulator: da9063: implement setter for voltage monitoring

Allow to en- and disable voltage monitoring from the device tree.
Consider that the da9063 only monitors under- *and* over-voltage
together, so both must be set to the same severity and value.

Reviewed-by: Adam Ward <DLG-Adam.Ward.opensource@dm.renesas.com>
Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com>
Link: https://lore.kernel.org/r/20230403-da9063-disable-unused-v3-2-cc4dc698864c@skidata.com


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