arm64: dts: imx8mm-venice-gw700x: fix mp5416 pmic config

Fix various MP5416 PMIC configurations:
 - Update regulator names per dt-bindings
 - ensure values fit among valid register values
 - add required regulator-max-microamp property
 - add regulator-always-on prop

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>