drm/i915: Suppress error message when GPU resets are disabled

If we do not have lowlevel support for reseting the GPU, or if the user
has explicitly disabled reseting the device, the failure is expected.
Since it is an expected failure, we should be using a lower priority
message than *ERROR*, perhaps NOTICE. In the absence of DRM_NOTICE, just
emit the expected failure as a DEBUG message.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1460565315-7748-10-git-send-email-chris@chris-wilson.co.uk