regulator: core: Fix resolve supply lookup issue

From Marek's log, the previous change modify the parent of rdev.
https://lore.kernel.org/all/58b92e75-f373-dae7-7031-8abd465bb874@samsung.com/

In 'regulator_resolve_supply', it uses the parent DT node of rdev as the
DT-lookup starting node. But the parent DT node may not exist. This will
cause the NULL supply issue.

This patch modify the parent of rdev back to the device that provides
from 'regulator_config' in 'regulator_register'.

Fixes: 8f3cbcd ("regulator: core: Use different devices for resource allocation and DT lookup")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1670981831-12583-1-git-send-email-u0084500@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: ChiYuan Huang

drivers/regulator/core.c

@@ -5539,7 +5539,7 @@ regulator_register(struct device *dev,
 
 	/* register with sysfs */
 	rdev->dev.class = &regulator_class;
-	rdev->dev.parent = dev;
+	rdev->dev.parent = config->dev;
 	dev_set_name(&rdev->dev, "regulator.%lu",
 		    (unsigned long) atomic_inc_return(&regulator_no));
 	dev_set_drvdata(&rdev->dev, rdev);