s390x/3270: Mark non-migratable and enable the device

Mark 3270 as non-migratable for the experimental stage. Enable
the 3270 device so that we can use x3270 client to operate the guest.

Run qemu with the arguments:
    -chardev socket,id=char3270_0,host=0.0.0.0,port=23,nowait,server,tn3270 \
    -device x-terminal3270,chardev=char3270_0,devno=fe.0.000a,id=terminal3270_0 \

There are some restrictions for the first stage: We don't support SSL
connections, multiple client connections and client resizing. Only
tested with the x3270 client.
Signed-off-by: NJing Liu <liujbjl@linux.vnet.ibm.com>
Signed-off-by: NYang Chen <bjcyang@linux.vnet.ibm.com>
Reviewed-by: NQingFeng Hao <haoqf@linux.vnet.ibm.com>
Reviewed-by: NDong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

default-configs/s390x-softmmu.mak

@@ -2,6 +2,7 @@ CONFIG_PCI=y
 CONFIG_VIRTIO_PCI=y
 CONFIG_VIRTIO=y
 CONFIG_SCLPCONSOLE=y
+CONFIG_TERMINAL3270=y
 CONFIG_S390_FLIC=y
 CONFIG_S390_FLIC_KVM=$(CONFIG_KVM)
 CONFIG_WDT_DIAG288=y

hw/char/Makefile.objs

@@ -29,3 +29,4 @@ common-obj-$(CONFIG_MILKYMIST) += milkymist-uart.o
 common-obj-$(CONFIG_SCLPCONSOLE) += sclpconsole.o sclpconsole-lm.o
 
 obj-$(CONFIG_VIRTIO) += virtio-serial-bus.o
+obj-$(CONFIG_TERMINAL3270) += terminal3270.o

hw/char/terminal3270.c

@@ -260,12 +260,18 @@ static Property terminal_properties[] = {
     DEFINE_PROP_END_OF_LIST(),
 };
 
+static const VMStateDescription terminal3270_vmstate = {
+    .name = TYPE_TERMINAL_3270,
+    .unmigratable = 1,
+};
+
 static void terminal_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     EmulatedCcw3270Class *ck = EMULATED_CCW_3270_CLASS(klass);
 
     dc->props = terminal_properties;
+    dc->vmsd = &terminal3270_vmstate;
     ck->init = terminal_init;
     ck->read_payload_3270 = read_payload_3270;
     ck->write_payload_3270 = write_payload_3270;