remove debug printk from DRM suspend path

Not sure how this snuck upstream, but it really doesn't belong there.  We
don't need a KERN_ERR printk in the suspend path to know what's going on (at
least not anymore).

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>