firmware: scmi_agent: add SCMI pin control protocol support

This patch adds SCMI pin control protocol support to make the pin
controller driver based on SCMI, such as
drivers/pinctrl/nxp/pinctrl-imx-scmi.c, can be bound to the SCMI agent
device whose protocol id is 0x19.

Signed-off-by: Alice Guo <alice.guo@nxp.com>
diff --git a/drivers/pinctrl/nxp/pinctrl-imx-scmi.c b/drivers/pinctrl/nxp/pinctrl-imx-scmi.c
index 5b7122b..aed47be 100644
--- a/drivers/pinctrl/nxp/pinctrl-imx-scmi.c
+++ b/drivers/pinctrl/nxp/pinctrl-imx-scmi.c
@@ -10,6 +10,7 @@
 #include <dm/devres.h>
 #include <dm/pinctrl.h>
 #include <scmi_agent.h>
+#include <scmi_agent-uclass.h>
 #include <scmi_protocols.h>
 
 #include "pinctrl-imx.h"
@@ -155,3 +156,10 @@
 	.ops = &imx_scmi_pinctrl_ops,
 	.flags = DM_FLAG_PRE_RELOC,
 };
+
+static struct scmi_proto_match match[] = {
+	{ .proto_id = SCMI_PROTOCOL_ID_PINCTRL },
+	{ /* Sentinel */ }
+};
+
+U_BOOT_SCMI_PROTO_DRIVER(scmi_pinctrl_imx, match);