drm/i915: move adjusted_x/y from crtc to cache.

Move adjusted_x/y from crtc to fbc cache.

Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1508270891-22186-2-git-send-email-juhapekka.heikkila@gmail.com


[vsyrjala: Add rudimentary commit message]
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>