twl4030-power: minor cleanup

Minor cleanups to the twl4030 power script support:  move its
init code out of the "add children" call (it adds no children!),
and move the power bus messages earlier in the header file to
unclutter the platform data section and since they're not used
only for those scripts.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>