virtio-gpu: OUT_OF_MEMORY if failing to create udmabuf

Respond with VIRTIO_GPU_RESP_ERR_OUT_OF_MEMORY if it fails to create
an udmabuf for the blob resource.

v2: consolidated return statments and removed an unnecessary style change

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20230627003453.5321-1-dongwon.kim@intel.com>

hw/display/virtio-gpu.c

@@ -651,8 +651,10 @@ static void virtio_gpu_do_set_scanout(VirtIOGPU *g,
         if (console_has_gl(scanout->con)) {
             if (!virtio_gpu_update_dmabuf(g, scanout_id, res, fb, r)) {
                 virtio_gpu_update_scanout(g, scanout_id, res, r);
-                return;
+            } else {
+                *error = VIRTIO_GPU_RESP_ERR_OUT_OF_MEMORY;
             }
+            return;
         }
 
         data = res->blob;