Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/parisc/include/asm/hardware.h b/arch/parisc/include/asm/hardware.h
index d6e1ed1..9d3d773 100644
--- a/arch/parisc/include/asm/hardware.h
+++ b/arch/parisc/include/asm/hardware.h
@@ -120,7 +120,7 @@
 extern void init_parisc_bus(void);
 extern struct device *hwpath_to_device(struct hardware_path *modpath);
 extern void device_to_hwpath(struct device *dev, struct hardware_path *path);
-
+extern int machine_has_merced_bus(void);
 
 /* inventory.c: */
 extern void do_memory_inventory(void);