drm/vmwgfx: Don't set struct drm_device.irq_enabled

The field drm_device.irq_enabled is only used by legacy drivers
with userspace modesetting. Don't set it in vmxgfx. All usage of
the field within vmwgfx can safely be removed.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Reviewed-by: Zack Rusin <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
Acked-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/vmwgfx/vmwgfx_irq.c

···
 	if (!(dev_priv->capabilities & SVGA_CAP_IRQMASK))
 		return;
 
-	if (!dev->irq_enabled)
-		return;
-
 	vmw_write(dev_priv, SVGA_REG_IRQMASK, 0);
 
 	status = vmw_irq_status_read(dev_priv);
 	vmw_irq_status_write(dev_priv, status);
 
-	dev->irq_enabled = false;
 	free_irq(dev->irq, dev);
 }
 
···
 {
 	int ret;
 
-	if (dev->irq_enabled)
-		return -EBUSY;
-
 	vmw_irq_preinstall(dev);
 
 	ret = request_threaded_irq(irq, vmw_irq_handler, vmw_thread_fn,
···
 	if (ret < 0)
 		return ret;
 
-	dev->irq_enabled = true;
 	dev->irq = irq;
 
 	return ret;