Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/freezer.c b/kernel/freezer.c
index b162b74..dc520f0 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * kernel/freezer.c - Function to freeze a process
  *
@@ -21,12 +22,6 @@
 bool pm_freezing;
 bool pm_nosig_freezing;
 
-/*
- * Temporary export for the deadlock workaround in ata_scsi_hotplug().
- * Remove once the hack becomes unnecessary.
- */
-EXPORT_SYMBOL_GPL(pm_freezing);
-
 /* protects freezing and frozen transitions */
 static DEFINE_SPINLOCK(freezer_lock);