Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
index 6d18b70..0a1898b 100644
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -1,7 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/highmem.h>
 #include <linux/export.h>
 #include <linux/swap.h> /* for totalram_pages */
-#include <linux/bootmem.h>
+#include <linux/memblock.h>
 
 void *kmap(struct page *page)
 {
@@ -111,7 +112,7 @@
 
 	/*
 	 * Explicitly reset zone->managed_pages because set_highmem_pages_init()
-	 * is invoked before free_all_bootmem()
+	 * is invoked before memblock_free_all()
 	 */
 	reset_all_zones_managed_pages();
 	for_each_zone(zone) {