twl4030: regulator driver

twl4030: regulator driver

Initial twl4030 "regulator framework" support.  Costs a bit over 2KB
memory at runtime, mostly data.  (Plus about 11KB for that framework.)

This only exports the LDO regulators for now, not the buck converters.
(Two of those buck converters should interact with cpufreq to reduce
voltage along with frequencies ...)

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