regulator: Update protection IRQ helper docs

The documentation of IRQ notification helper had still references to
first RFC implementation which called BUG() while trying to protect the
hardware. Behaviour was improved as calling the BUG() was not a proper
solution. Current implementation attempts to call poweroff if handling
of potentially damaging error notification fails. Update the
documentation to reflect the actual behaviour.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/0c9cc4bcf20c3da66fd5a85c97ee4288e5727538.1637233864.git.matti.vaittinen@fi.rohmeurope.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/regulator/driver.h

@@ -499,7 +499,8 @@ struct regulator_irq_data {
  *		best to shut-down regulator(s) or reboot the SOC if error
  *		handling is repeatedly failing. If fatal_cnt is given the IRQ
  *		handling is aborted if it fails for fatal_cnt times and die()
- *		callback (if populated) or BUG() is called to try to prevent
+ *		callback (if populated) is called. If die() is not populated
+ *		poweroff for the system is attempted in order to prevent any
  *		further damage.
  * @reread_ms:	The time which is waited before attempting to re-read status
  *		at the worker if IC reading fails. Immediate re-read is done
@@ -516,11 +517,12 @@ struct regulator_irq_data {
  * @data:	Driver private data pointer which will be passed as such to
  *		the renable, map_event and die callbacks in regulator_irq_data.
  * @die:	Protection callback. If IC status reading or recovery actions
- *		fail fatal_cnt times this callback or BUG() is called. This
- *		callback should implement a final protection attempt like
- *		disabling the regulator. If protection succeeded this may
- *		return 0. If anything else is returned the core assumes final
- *		protection failed and calls BUG() as a last resort.
+ *		fail fatal_cnt times this callback is called or system is
+ *		powered off. This callback should implement a final protection
+ *		attempt like disabling the regulator. If protection succeeded
+ *		die() may return 0. If anything else is returned the core
+ *		assumes final protection failed and attempts to perform a
+ *		poweroff as a last resort.
  * @map_event:	Driver callback to map IRQ status into regulator devices with
  *		events / errors. NOTE: callback MUST initialize both the
  *		errors and notifs for all rdevs which it signals having