Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/testing/selftests/timers/nanosleep.c b/tools/testing/selftests/timers/nanosleep.c
index 8adb0bb..71b5441 100644
--- a/tools/testing/selftests/timers/nanosleep.c
+++ b/tools/testing/selftests/timers/nanosleep.c
@@ -142,6 +142,7 @@
 			continue;
 
 		printf("Nanosleep %-31s ", clockstring(clockid));
+		fflush(stdout);
 
 		length = 10;
 		while (length <= (NSEC_PER_SEC * 10)) {