[S390] cio: allow enable_facility from outside init functions

Prepare chsc_enable_facility to be used from outside init functions.
Use static memory for the chsc call and protect its access by a
spinlock (although there is no concurrent usage).

Cc: <stable@kernel.org>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 2769da5..19635d4 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -870,15 +870,10 @@
 
 	/* Try to enable MSS. */
 	ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
-	switch (ret) {
-	case 0: /* Success. */
-		max_ssid = __MAX_SSID;
-		break;
-	case -ENOMEM:
-		goto out;
-	default:
+	if (ret)
 		max_ssid = 0;
-	}
+	else /* Success. */
+		max_ssid = __MAX_SSID;
 
 	ret = slow_subchannel_init();
 	if (ret)