Linux 4.8.21

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/Makefile b/Makefile
index e75ae4c..2c021b1 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 VERSION = 4
 PATCHLEVEL = 8
-SUBLEVEL = 20
+SUBLEVEL = 21
 EXTRAVERSION =
 NAME = Psychotic Stoned Sheep