The nv50 pgraph handler (for example) could reenable pgraph fifo access
and that would be bad when pgraph context is being unloaded (we need the
guarantee a ctxprog isn't running).
Signed-off-by: NMaarten Maathuis <madman2003@gmail.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>