Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/testing/selftests/timers/mqueue-lat.c b/tools/testing/selftests/timers/mqueue-lat.c
index 1867db5..7916cf5 100644
--- a/tools/testing/selftests/timers/mqueue-lat.c
+++ b/tools/testing/selftests/timers/mqueue-lat.c
@@ -102,6 +102,7 @@
 	int ret;
 
 	printf("Mqueue latency :                          ");
+	fflush(stdout);
 
 	ret = mqueue_lat_test();
 	if (ret < 0) {