regulator: Documentation fix for regulator error notification helper

The helper to send IRQ notification for regulator errors had still
old description mentioning calling BUG() as a last resort when
error status reading has kept failing for more times than a given
threshold.

The impementation calling BUG() did never end-up in-tree but was
replaced by hopefully more sophisticated handler trying to power-off
the system.

Fix the documentation to reflect actual behaviour.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/20210823075651.GA3717293@localhost.localdomain
Signed-off-by: Mark Brown <broonie@kernel.org>