regulator: core: Let boot-on regulators be powered off

Boot-on regulators are always kept on because their use_count value
is now incremented at boot time and never cleaned.

Only increment count value for alway-on regulators.
regulator_late_cleanup() is now able to power off boot-on regulators
when unused.

Fixes: 05f224ca ("regulator: core: Clean enabling always-on regulators + their supplies")
Signed-off-by: Pascal Paillet <p.paillet@st.com>
Link: https://lore.kernel.org/r/20191113102737.27831-1-p.paillet@st.com


Signed-off-by: Mark Brown <broonie@kernel.org>