regulator: debug early supply resolving

Help debugging the case when set_machine_constraints() needs to be
repeated.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de> # stpmic1
Link: https://lore.kernel.org/r/f9cba575580369e46661a9278ee6c6a8d8564c2a.1605226675.git.mirq-linux@rere.qmqm.pl


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