qcom_smd-regulator: Unused regulators are not disabled after boot

[stephan-gh]

This happens because qcom_smd-regulator cannot detect if a regulator is actually enabled. So it pretends that all of them are disabled at boot, and keeps them as-is.

It might be possible to use regulator-boot-on for this, as it temporarily enables the regulator, making qcom_smd-regulator aware of the state. But at the moment regulator-boot-on is equivalent to regulator-always-on for some reason (might be regression?).