regulator: remove locking around regulator_notifier_call_chain()

regulator_notifier_call_chain() doesn't need rdev lock and rdev's
existence is assumed in the code anyway. Remove the locks from drivers.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/42393f66dcc4d80dcd9797be45216b4035aa96cb.1597032945.git.mirq-linux@rere.qmqm.pl


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