[S390] stp support.

Add support for clock synchronization with the server time protocol.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/drivers/s390/s390mach.c b/drivers/s390/s390mach.c
index fe75152..834e9ee 100644
--- a/drivers/s390/s390mach.c
+++ b/drivers/s390/s390mach.c
@@ -458,6 +458,10 @@
 			etr_sync_check();
 		if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
 			etr_switch_to_local();
+		if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
+			stp_sync_check();
+		if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
+			stp_island_check();
 	}
 
 	if (mci->se)