Mostly obvious simplifications.

The i915 pread/pwrite ioctls, intel_overlay_put_image and
nouveau_gem_new were incorrectly using the locked versions
without locking: this is also fixed in this patch.
Signed-off-by: NLuca Barbieri <luca@luca-barbieri.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>