firmware: scmi: use protocol node name to bind the scmi regulator driver

In scmi firmware driver, it is better to bind the scmi protocol driver
"scmi_voltage_domain" with the node name of the protocol 17 and not
the sub-node named "regulator", because is a fixed string which doesn't
provide information and because it is not aligned with the other scmi
protocol nodes.

For example on stm32mp135f-dk board with device tree in stm32mp131.dtsi

scmi: scmi {
	compatible = "linaro,scmi-optee";
	#address-cells = <1>;
	#size-cells = <0>;
	linaro,optee-channel-id = <0>;
	shmem = <&scmi_shm>;
	scmi_clk: protocol@14 {
		reg = <0x14>;
		#clock-cells = <1>;
	};
	scmi_reset: protocol@16 {
		reg = <0x16>;
		#reset-cells = <1>;
	};
	scmi_voltd: protocol@17 {
		reg = <0x17>;
		scmi_regu: regulators {
			#address-cells = <1>;
			#size-cells = <0>;
			scmi_reg11: voltd-reg11 {
				reg = <VOLTD_SCMI_REG11>;
				regulator-name = "reg11";
			};
			scmi_reg18: voltd-reg18 {
				reg = <VOLTD_SCMI_REG18>;
				regulator-name = "reg18";
			};
			scmi_usb33: voltd-usb33 {
				reg = <VOLTD_SCMI_USB33>;
				regulator-name = "usb33";
			};
		};
	};
};

Before the patch:

> dm tree

 scmi_agent    0  [ + ]   scmi-over-optee       |-- scmi
 clk           1  [ + ]   scmi_clk              |   |-- protocol@14
 ...
 reset         1  [   ]   scmi_reset_domain     |   |-- protocol@16
 nop           2  [ + ]   scmi_voltage_domain   |   `-- regulators
 regulator     0  [ + ]   scmi_regulator        |       |-- voltd-reg11
 regulator     1  [ + ]   scmi_regulator        |       |-- voltd-reg18
 regulator     2  [ + ]   scmi_regulator        |       |-- voltd-usb33
 ...

after the patch:

> dm tree

 scmi_agent    0  [ + ]   scmi-over-optee       |-- scmi
 clk           1  [ + ]   scmi_clk              |   |-- protocol@14
 ...
 reset         1  [   ]   scmi_reset_domain     |   |-- protocol@16
 nop           2  [ + ]   scmi_voltage_domain   |   `-- protocol@17
 regulator     0  [ + ]   scmi_regulator        |       |-- voltd-reg11
 regulator     1  [ + ]   scmi_regulator        |       |-- voltd-reg18
 regulator     2  [ + ]   scmi_regulator        |       |-- voltd-usb33
 ...

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/drivers/firmware/scmi/scmi_agent-uclass.c b/drivers/firmware/scmi/scmi_agent-uclass.c
index 8f48de3..9a32678 100644
--- a/drivers/firmware/scmi/scmi_agent-uclass.c
+++ b/drivers/firmware/scmi/scmi_agent-uclass.c
@@ -60,6 +60,7 @@
 {
 	int ret = 0;
 	ofnode node;
+	const char *name;
 
 	dev_for_each_subnode(node, dev) {
 		struct driver *drv = NULL;
@@ -71,6 +72,7 @@
 		if (ofnode_read_u32(node, "reg", &protocol_id))
 			continue;
 
+		name = ofnode_get_name(node);
 		switch (protocol_id) {
 		case SCMI_PROTOCOL_ID_CLOCK:
 			if (IS_ENABLED(CONFIG_CLK_SCMI))
@@ -100,8 +102,7 @@
 			continue;
 		}
 
-		ret = device_bind(dev, drv, ofnode_get_name(node), NULL, node,
-				  NULL);
+		ret = device_bind(dev, drv, name, NULL, node, NULL);
 		if (ret)
 			break;
 	}