virtio: add missing MODULE_DESCRIPTION() macros

With ARCH=sh, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/virtio/virtio.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/virtio/virtio_ring.o

Add the missing invocations of the MODULE_DESCRIPTION() macro.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Message-Id: <20240702-md-sh-drivers-virtio-v1-1-cf7325ab6ccc@quicinc.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio.c

@@ -609,4 +609,5 @@ static void __exit virtio_exit(void)
 core_initcall(virtio_init);
 module_exit(virtio_exit);
 
+MODULE_DESCRIPTION("Virtio core interface");
 MODULE_LICENSE("GPL");

drivers/virtio/virtio_ring.c

@@ -3246,4 +3246,5 @@ void virtqueue_dma_sync_single_range_for_device(struct virtqueue *_vq,
 }
 EXPORT_SYMBOL_GPL(virtqueue_dma_sync_single_range_for_device);
 
+MODULE_DESCRIPTION("Virtio ring implementation");
 MODULE_LICENSE("GPL");