arm64: dts: mt8173: Add PMIC wrapper device node

This adds the device node for the PMIC wrapper.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>