Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/s390/cio/ioasm.c b/drivers/s390/cio/ioasm.c
index 14d3283..08eb102 100644
--- a/drivers/s390/cio/ioasm.c
+++ b/drivers/s390/cio/ioasm.c
@@ -233,6 +233,7 @@
 
 	return ccode;
 }
+EXPORT_SYMBOL(hsch);
 
 static inline int __xsch(struct subchannel_id schid)
 {