drm/qxl: Do not cause spice-server to clean our objects

If objects are moved back from system memory to VRAM (and spice id
created again) memory is already initialized so we need to set flag
to not clear memory.
If you don't do it after a while using desktop many images turns to
black or transparents.
Signed-off-by: NFrediano Ziglio <fziglio@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: NDave Airlie <airlied@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/qxl/qxl_cmd.c

@@ -505,6 +505,7 @@ int qxl_hw_surface_alloc(struct qxl_device *qdev,
 
 	cmd = (struct qxl_surface_cmd *)qxl_release_map(qdev, release);
 	cmd->type = QXL_SURFACE_CMD_CREATE;
+	cmd->flags = QXL_SURF_FLAG_KEEP_DATA;
 	cmd->u.surface_create.format = surf->surf.format;
 	cmd->u.surface_create.width = surf->surf.width;
 	cmd->u.surface_create.height = surf->surf.height;