mfd: twl4030-power: Accept standard property for power controller

Instead of only accepting the ti specific properties accept also
the standard property. For uniformity, search in the parent node
for the tag. The code for powering off is also isolated from the
rest in this file. So it is a pure Linux design decision to put it
here.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Link: https://lore.kernel.org/r/20240217082007.3238948-6-andreas@kemnade.info


Signed-off-by: Lee Jones <lee@kernel.org>