Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/testing/selftests/timers/threadtest.c b/tools/testing/selftests/timers/threadtest.c
index 759c9c0..cf3e489 100644
--- a/tools/testing/selftests/timers/threadtest.c
+++ b/tools/testing/selftests/timers/threadtest.c
@@ -163,6 +163,7 @@
 	strftime(buf, 255, "%a, %d %b %Y %T %z", localtime(&start));
 	printf("%s\n", buf);
 	printf("Testing consistency with %i threads for %ld seconds: ", thread_count, runtime);
+	fflush(stdout);
 
 	/* spawn */
 	for (i = 0; i < thread_count; i++)