feat(drivers/scmi-msg): add power domain protocol

Add SCMI power domain protocol, with POWER_STATE_NOTIFY and
POWER_STATE_CHANGE_REQUESTED_NOTIFY not implemented.

Reviewed-by: Jacky Bai <ping.bai@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Change-Id: Ia7c4db57c4c702667f8eaa630c924016e4a8bde0
diff --git a/drivers/scmi-msg/common.h b/drivers/scmi-msg/common.h
index ef5953b..62f3087 100644
--- a/drivers/scmi-msg/common.h
+++ b/drivers/scmi-msg/common.h
@@ -13,6 +13,7 @@
 
 #include "base.h"
 #include "clock.h"
+#include "power_domain.h"
 #include "reset_domain.h"
 
 #define SCMI_VERSION			0x20000U
@@ -111,6 +112,13 @@
 scmi_msg_handler_t scmi_msg_get_rstd_handler(struct scmi_msg *msg);
 
 /*
+ * scmi_msg_get_pd_handler - Return a handler for a power domain message
+ * @msg - message to process
+ * Return a function handler for the message or NULL
+ */
+scmi_msg_handler_t scmi_msg_get_pd_handler(struct scmi_msg *msg);
+
+/*
  * Process Read, process and write response for input SCMI message
  *
  * @msg: SCMI message context