[S390] pfault: always enable service signal interrupt

Always enable the service signal subclass mask bit in cr0, if pfault
is available. That way we use the normal cpu hotplug way to propagate
the subclass mask bit in cr0 instead of open coding it.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index a0f9e73..e46ba29 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -485,7 +485,6 @@
 		"2:\n"
 		EX_TABLE(0b,1b)
 		: "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
-        __ctl_set_bit(0, 9);
         return rc;
 }
 
@@ -500,7 +499,6 @@
 
 	if (!MACHINE_IS_VM || pfault_disable)
 		return;
-	__ctl_clear_bit(0,9);
 	asm volatile(
 		"	diag	%0,0,0x258\n"
 		"0:\n"
@@ -615,6 +613,7 @@
 	rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
 	if (rc)
 		goto out_pfault;
+	ctl_set_bit(0, 9);
 	hotcpu_notifier(pfault_cpu_notify, 0);
 	return 0;