Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/um/asm/barrier.h b/arch/x86/um/asm/barrier.h
index f31e5d9..165be7f 100644
--- a/arch/x86/um/asm/barrier.h
+++ b/arch/x86/um/asm/barrier.h
@@ -2,14 +2,7 @@
 #ifndef _ASM_UM_BARRIER_H_
 #define _ASM_UM_BARRIER_H_
 
-#include <asm/asm.h>
-#include <asm/segment.h>
-#include <asm/cpufeatures.h>
-#include <asm/cmpxchg.h>
-#include <asm/nops.h>
-
-#include <linux/kernel.h>
-#include <linux/irqflags.h>
+#include <asm/alternative.h>
 
 /*
  * Force strict CPU ordering.
@@ -30,9 +23,6 @@
 
 #endif /* CONFIG_X86_32 */
 
-#define dma_rmb()	barrier()
-#define dma_wmb()	barrier()
-
 #include <asm-generic/barrier.h>
 
 #endif