regulator: da9211: Pass NULL data with OVER_CURRENT event

According to the documentation, no data is passed with the OVER_CURRENT
regulator notifier event.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: James Ban <james.ban.opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@kernel.org>