frontend/va/image: add pipe flush for vlVaPutImage

To fix synchronization issue between multimedia queue and gfx queue.
Adding flush call will let multimedia queue to wait for the content of gfx
command buffer to be executed, for the case where there is dependency
between these two queues.

Fixes: 2f50dea218 ("radeonsi: always use a staging texture for linear 1D textures in VRAM")
Signed-off-by: Boyuan Zhang <boyuan.zhang@amd.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
(cherry picked from commit 27209e63ea)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9995>

src/gallium/frontends/va/image.c

@@ -696,6 +696,7 @@ vlVaPutImage(VADriverContextP ctx, VASurfaceID surface, VAImageID image,
          }
       }
    }
+   drv->pipe->flush(drv->pipe, NULL, 0);
    mtx_unlock(&drv->mutex);
 
    return VA_STATUS_SUCCESS;