Minor cleanups to the twl403 regulator driver, mostly enabled
by other recent changes:  comments, shrink memory usage, add
definition for one bit.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>