NVIDIA do that at startup too on Fermi, so perhaps the heap of 0x10
intrs we receive are normal and we can ignore them.

On Kepler NVIDIA *don't* do this, but the hardware appears to come up
with the bit masked off by default - so that's probably why :)

This should silence some interrupt spam seen on Fermi+ boards.

Backported patch from reworked nouveau kernel tree.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>