drm/virtio: Add */ in block comments to separate line

This patch fixes the checkpatch.pl warning:

virtgpu_ioctl.c:551: WARNING: Block comments use a trailing */ on a
separate line
...

Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/f0bd4104a7d26bf7561c3a2b4632041c5411f1f2.1519343668.git.rodrigosiqueiramelo@gmail.com


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>