virtio-gpu: fix ioctl and expose the fixed status to userspace.

This exposes to mesa that it can use the fixed ioctl for querying
later cap sets, cap set 1 is forever frozen in time.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20180221015003.22884-1-airlied@gmail.com


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