[S390] Fix smsgiucv init on no iucv machines

smsgiucv is a driver that relies on iucv to work properly. If
iucv ans smsgiucv are compiled into the kernel and run on an
lpar the following scenario happens:
iucv is initialized early as a subsystem. It checks for z/VM and
returns with EPROTONOTSUPPORT. Later smsgiucv tries to run
driver_register with iucv_bus as bus. As this bus is not
initialized the driver core and list debugging issue several
warnings and oopses.

Solution is to let smsgiucv also check for z/VM and return
EPROTONOTSUPPORT as well.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/net/smsgiucv.c

@@ -148,6 +148,10 @@ static int __init smsg_init(void)
 {
 	int rc;
 
+	if (!MACHINE_IS_VM) {
+		rc = -EPROTONOSUPPORT;
+		goto out;
+	}
 	rc = driver_register(&smsg_driver);
 	if (rc != 0)
 		goto out;