sparc64: Fix build warnings with gcc 7.

arch/sparc/kernel/ds.c: In function ‘register_services’:
arch/sparc/kernel/ds.c:912:3: error: ‘strcpy’: writing at least 1 byte
into a region of size 0 overflows the destination
Reported-by: NAnatoly Pugachev <matorola@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/kernel/ds.c

@@ -909,7 +909,7 @@ static int register_services(struct ds_info *dp)
 		pbuf.req.handle = cp->handle;
 		pbuf.req.major = 1;
 		pbuf.req.minor = 0;
-		strcpy(pbuf.req.svc_id, cp->service_id);
+		strcpy(pbuf.id_buf, cp->service_id);
 
 		err = __ds_send(lp, &pbuf, msg_len);
 		if (err > 0)