drm/udl: disable fb_defio by default

commit 677d23b70bf949f75746c80cbae92c233c6b5e2a upstream.

There seems to be a bad interaction between gem/shmem and defio on top,
I get list corruption on the page lru in the shmem code.

Turn it off for now until we get some more digging done.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>