drm/nouveau: fix m2mf copy to tiled gart

commit ce8f7699 upstream.

Commit de7b7d59 introduced tiled GART, but a linear copy is
still performed. This may result in errors on eviction, fix it by
checking tiling from memtype.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>