Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h
index 76c2fbc..dc1da02 100644
--- a/include/linux/kvm_irqfd.h
+++ b/include/linux/kvm_irqfd.h
@@ -1,12 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
  *
  * irqfd: Allows an fd to be used to inject an interrupt to the guest
  * Credit goes to Avi Kivity for the original idea.