regulator: da9062: Fix notifier mutex lock warning

The mutex for the regulator_dev must be controlled by the caller of
the regulator_notifier_call_chain(), as described in the comment
for that function.

Failure to mutex lock and unlock surrounding the notifier call results
in a kernel WARN_ON_ONCE() which will dump a backtrace for the
regulator_notifier_call_chain() when that function call is first made.
The mutex can be controlled using the regulator_lock/unlock() API.

Fixes: 4068e518 ("regulator: da9062: DA9062 regulator driver")
Suggested-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/da9062-regulator.c

@@ -974,8 +974,10 @@ static irqreturn_t da9062_ldo_lim_event(int irq, void *data)
 			continue;
 
 		if (BIT(regl->info->oc_event.lsb) & bits) {
+			regulator_lock(regl->rdev);
 			regulator_notifier_call_chain(regl->rdev,
 					REGULATOR_EVENT_OVER_CURRENT, NULL);
+			regulator_unlock(regl->rdev);
 			handled = IRQ_HANDLED;
 		}
 	}