Revert "drm: Don't allow interruptions when opening debugfs/crc"

This reverts

commit b8dfa821
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Fri Apr 7 12:17:12 2017 +0100
    drm: Don't allow interruptions when opening debugfs/crc

It reportedly breaks things, so let's revert now and try again later.

Fixes: b8dfa821

 ("drm: Don't allow interruptions when opening debugfs/crc")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>