virtio-gpu: make virtio_gpu_ops static

Reference it via ops pointer instead, simliar to the vga one.
Removes hard symbol reference, needed to build virtio-gpu modular.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20200914134224.29769-6-kraxel@redhat.com

include/hw/virtio/virtio-gpu.h

@@ -106,6 +106,7 @@ struct VirtIOGPUBase {
 
     struct virtio_gpu_base_conf conf;
     struct virtio_gpu_config virtio_config;
+    const GraphicHwOps *hw_ops;
 
     bool use_virgl_renderer;
     int renderer_blocked;
@@ -171,8 +172,6 @@ struct VhostUserGPU {
     bool backend_blocked;
 };
 
-extern const GraphicHwOps virtio_gpu_ops;
-
 #define VIRTIO_GPU_FILL_CMD(out) do {                                   \
         size_t s;                                                       \
         s = iov_to_buf(cmd->elem.out_sg, cmd->elem.out_num, 0,          \