power: reset: syscon-poweroff: get regmap from parent node

Just like syscon-reboot device, the syscon-poweroff is supposed to be a
child of syscon node, thus we can take the same approach as
syscon-poweroff: deprecate the 'regmap' field in favor of taking it from
the parent's node.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/reset/syscon-poweroff.c

···
 
 	map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
 	if (IS_ERR(map)) {
-		dev_err(dev, "unable to get syscon");
-		return PTR_ERR(map);
+		map = syscon_node_to_regmap(dev->parent->of_node);
+		if (IS_ERR(map)) {
+			dev_err(dev, "unable to get syscon");
+			return PTR_ERR(map);
+		}
 	}
 
 	if (of_property_read_u32(dev->of_node, "offset", &offset)) {