cairnsmore: Don't bother timing dynclock detection, since there's no standard way to log it accurately

driver-cairnsmore.c

@@ -82,8 +82,6 @@ bool cairnsmore_supports_dynclock(int fd)
 {
 	if (!cairnsmore_send_cmd(fd, 0, 1, true))
 		return false;
-	struct timeval tv_start, elapsed;
-	gettimeofday(&tv_start, NULL);
 	if (!cairnsmore_send_cmd(fd, 0, 1, true))
 		return false;
 
@@ -95,9 +93,8 @@ bool cairnsmore_supports_dynclock(int fd)
 			.work_restart_fd = -1,
 		};
 		icarus_gets((unsigned char*)&nonce, fd, &tv_finish, &dummy, 1);
-		timersub(&tv_finish, &tv_start, &elapsed);
 	}
-	applog(LOG_DEBUG, "Cairnsmore dynclock detection... Got %08x in %d.%06ds", nonce, elapsed.tv_sec, elapsed.tv_usec);
+	applog(LOG_DEBUG, "Cairnsmore dynclock detection... Got %08x", nonce);
 	switch (nonce) {
 		case 0x00949a6f:  // big    endian
 		case 0x6f9a9400:  // little endian