Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/powerpc/include/asm/swiotlb.h b/arch/powerpc/include/asm/swiotlb.h
index f65ecf5..3c1a1cd 100644
--- a/arch/powerpc/include/asm/swiotlb.h
+++ b/arch/powerpc/include/asm/swiotlb.h
@@ -1,11 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
  * Copyright (C) 2009 Becky Bruce, Freescale Semiconductor
- *
- * 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, or (at your
- * option) any later version.
- *
  */
 
 #ifndef __ASM_SWIOTLB_H
@@ -13,12 +8,7 @@
 
 #include <linux/swiotlb.h>
 
-extern const struct dma_map_ops powerpc_swiotlb_dma_ops;
-
 extern unsigned int ppc_swiotlb_enable;
-int __init swiotlb_setup_bus_notifier(void);
-
-extern void pci_dma_dev_setup_swiotlb(struct pci_dev *pdev);
 
 #ifdef CONFIG_SWIOTLB
 void swiotlb_detect_4g(void);