powerpc/powernv: Use struct opal_prd_msg in more places

Use the newly added struct opal_prd_msg in some other functions that
operate on opal_prd messages, rather than using other types.

Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://msgid.link/[e-mail]

arch/powerpc/platforms/powernv/opal-prd.c

···
 		size_t count, loff_t *ppos)
 {
 	struct opal_prd_msg_header hdr;
+	struct opal_prd_msg *msg;
 	ssize_t size;
-	void *msg;
 	int rc;
 
 	size = sizeof(hdr);
···
 
 static int opal_prd_release(struct inode *inode, struct file *file)
 {
-	struct opal_prd_msg_header msg;
+	struct opal_prd_msg msg;
 
-	msg.size = cpu_to_be16(sizeof(msg));
-	msg.type = OPAL_PRD_MSG_TYPE_FINI;
+	msg.header.size = cpu_to_be16(sizeof(msg));
+	msg.header.type = OPAL_PRD_MSG_TYPE_FINI;
 
-	opal_prd_msg((struct opal_prd_msg *)&msg);
+	opal_prd_msg(&msg);
 
 	atomic_xchg(&prd_usage, 0);