virtio: add missing MODULE_DESCRIPTION() macro

make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/virtio/virtio_dma_buf.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Message-Id: <20240602-md-virtio_dma_buf-v1-1-ce602d47e257@quicinc.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_dma_buf.c

@@ -85,5 +85,6 @@ int virtio_dma_buf_get_uuid(struct dma_buf *dma_buf,
 }
 EXPORT_SYMBOL(virtio_dma_buf_get_uuid);
 
+MODULE_DESCRIPTION("dma-bufs for virtio exported objects");
 MODULE_LICENSE("GPL");
 MODULE_IMPORT_NS(DMA_BUF);