Revert unrelated part of "drm: simplify the locking in the GETCRTC ioctl"

v2 of the commit 2c77bb29 ("drm: simplify the locking in the GETCRTC ioctl")
accidentally introduced a unrelated change in intel_display.c, revert the
unrelated change.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: 2c77bb29 ("drm: simplify the locking in the GETCRTC ioctl")
Reported-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/6be47261-475f-c190-af56-c136677246d9@linux.intel.com