Linux 5.15.21

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/Makefile b/Makefile
index 3643400..b4770cd 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 VERSION = 5
 PATCHLEVEL = 15
-SUBLEVEL = 20
+SUBLEVEL = 21
 EXTRAVERSION =
 NAME = Trick or Treat