regulator: Mention regulator id in error message about dummy supplies

With the name that is currently looked up it is considerably easier to
understand the issue and fix the warning.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20240507104703.2070117-2-u.kleine-koenig@pengutronix.de


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