drm/i915: remove set but unused variables

Caught by "make W=1 drivers/gpu/drm/i915/".

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --cc drivers/gpu/drm/i915/intel_display.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_dp.c
Simple merge

diff --cc drivers/gpu/drm/i915/intel_hdmi.c
Simple merge