regulator: core: don't ignore errors from event forwarding setup

regulator: core: don't ignore errors from event forwarding setup

Receiving and forwarding critical supply events seems like they're
important information and we shouldn't ignore errors occurring during
registration for such events.

With this change the supply is unset on event registration failure,
allowing us to potentially retry another time.

Fixes: 433e294c3c5b ("regulator: core: forward undervoltage events downstream by default")
Signed-off-by: André Draszik <andre.draszik@linaro.org>
Link: https://patch.msgid.link/20260109-regulators-defer-v2-6-1a25dc968e60@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>