qxl: call qemu_spice_display_init_common for secondary devices

Fixes this 2.10 regression:

  $ qemu-system-x86_64  -cpu host -m 6144 -vga qxl -device qxl
  qemu-system-x86_64: util/qemu-thread-posix.c:64: qemu_mutex_lock: Assertion `mutex->initialized' failed.

Reported-by: ademaria@redhat.com
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20170814231552.24593-1-pbonzini@redhat.com
Cc: kraxel@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/display/qxl.c

@@ -2054,6 +2054,7 @@ static void qxl_realize_common(PCIQXLDevice *qxl, Error **errp)
     uint32_t pci_device_rev;
     uint32_t io_size;
 
+    qemu_spice_display_init_common(&qxl->ssd);
     qxl->mode = QXL_MODE_UNDEFINED;
     qxl->generation = 1;
     qxl->num_memslots = NUM_MEMSLOTS;
@@ -2176,7 +2177,6 @@ static void qxl_realize_primary(PCIDevice *dev, Error **errp)
     portio_list_add(&qxl->vga_port_list, pci_address_space_io(dev), 0x3b0);
 
     vga->con = graphic_console_init(DEVICE(dev), 0, &qxl_ops, qxl);
-    qemu_spice_display_init_common(&qxl->ssd);
 
     qxl_realize_common(qxl, &local_err);
     if (local_err) {