regulator: add missing call to of_node_put()

In one of the error paths of the for_each_child_of_node() loop,
add missing call to of_node_put().

Fix the following coccicheck warning:
./drivers/regulator/scmi-regulator.c:343:1-23: WARNING: Function
"for_each_child_of_node" should have of_node_put() before return around
line 347.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/1614303575-27436-1-git-send-email-yang.lee@linux.alibaba.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/scmi-regulator.c

@@ -343,8 +343,10 @@ static int scmi_regulator_probe(struct scmi_device *sdev)
 	for_each_child_of_node(np, child) {
 		ret = process_scmi_regulator_of_node(sdev, child, rinfo);
 		/* abort on any mem issue */
-		if (ret == -ENOMEM)
+		if (ret == -ENOMEM) {
+			of_node_put(child);
 			return ret;
+		}
 	}
 
 	/*