power: regulator: scmi: Move regulator subnode hack to scmi_regulator

The current code attempts to bind scmi_voltage_domain to regulator subnode
of the SCMI protocol node, so scmi_voltage_domain can then bind regulators
directly to subnodes of its node. This kind of behavior should not be in
core code, move it into scmi_voltage_domain driver code. Let the driver
descend into regulator node and bind regulators to its subnodes.

Fixes: 1f213ee4dbf2 ("firmware: scmi: voltage regulator")
Signed-off-by: Marek Vasut <marex@denx.de>
[Alice Guo: Fix scmi_regulator_bind]
Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/drivers/firmware/scmi/scmi_agent-uclass.c b/drivers/firmware/scmi/scmi_agent-uclass.c
index 8c907c3..e6e43ae 100644
--- a/drivers/firmware/scmi/scmi_agent-uclass.c
+++ b/drivers/firmware/scmi/scmi_agent-uclass.c
@@ -427,14 +427,8 @@
 			break;
 		case SCMI_PROTOCOL_ID_VOLTAGE_DOMAIN:
 			if (IS_ENABLED(CONFIG_DM_REGULATOR_SCMI) &&
-			    scmi_protocol_is_supported(dev, protocol_id)) {
-				node = ofnode_find_subnode(node, "regulators");
-				if (!ofnode_valid(node)) {
-					dev_err(dev, "no regulators node\n");
-					return -ENXIO;
-				}
+			    scmi_protocol_is_supported(dev, protocol_id))
 				drv = DM_DRIVER_GET(scmi_voltage_domain);
-			}
 			break;
 		default:
 			break;