drm/i915: pass adjusted_mode to intel_choose_pipe_bpp_dither(), again

Daniel's backmerge

commit c2fb7916
Merge: 29de6ce5 6f0c0580
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Mon Oct 22 14:34:51 2012 +0200

    Merge tag 'v3.7-rc2' into drm-intel-next-queued

to solve conflicts blew up (either git or Daniel was trying to be too
clever for their own good; it's usually convenient to blame tools ;) and
caused the changes of

commit 0c96c65b
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Wed Sep 26 18:43:10 2012 +0300

    drm/i915: use adjusted_mode instead of mode for checking the 6bpc force flag

in ironlake_crtc_mode_set() to be dropped.

Fix the call in ironlake_crtc_mode_set() again, and while at it, also fix
the new, copy-pasted haswell_crtc_mode_set() to use adjusted_mode.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>