Make the regulator setup code simpler and more consistent:

 - The only difference between "boot_on" and "always_on" is
   that an "always_on" regulator won't be disabled.  Both will
   be active (and usecount will be 1) on return from setup.

 - Regulators not marked as "boot_on" or "always_on" won't
   be active (and usecount will be 0) on return from setup.

The exception to that simple policy is when there's a non-Linux
interface to the regulator ... e.g. if either a DSP or the CPU
running Linux can enable the regulator, and the DSP needs it to
be on, then it will be on.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>