Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index e63799a..3734cd8 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -14,6 +14,7 @@
 #define SYS_POWER_OFF	0x0003	/* Notify of system power off */
 
 enum reboot_mode {
+	REBOOT_UNDEFINED = -1,
 	REBOOT_COLD = 0,
 	REBOOT_WARM,
 	REBOOT_HARD,
@@ -21,6 +22,7 @@
 	REBOOT_GPIO,
 };
 extern enum reboot_mode reboot_mode;
+extern enum reboot_mode panic_reboot_mode;
 
 enum reboot_type {
 	BOOT_TRIPLE	= 't',