regulator: Flag uncontrollable regulators as always_on

regulator: Flag uncontrollable regulators as always_on

While we currently assume that regulators with no control available are
just uncontionally enabled this isn't always as clearly displayed to
users as is desirable, for example the code for disabling unused
regulators will log that it is about to disable them. Clean this up a
bit by setting always_on during constraint evaluation if we have no
available mechanism for controlling the regualtor so things that check
the constraint will do the right thing.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220325144637.1543496-1-broonie@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>