regulator: wm8350: Pass NULL data with REGULATION_OUT and UNDER_VOLTAGE events

According to the documentation, no data is passed with the
REGULATION_OUT and UNDER_VOLTAGE regulator notifier events.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>