drm/i915: there's no cxsr on ilk

Already discovered in

commit 5a117db77e47e3946d1aaa7ce8deafafd9d76746
Author: Eugeni Dodonov <eugeni.dodonov@intel.com>
Date:   Thu Jan 5 09:34:29 2012 -0200

    drm/i915: there is no pipe CxSR on ironlake

but we've failed to rip out the code from the ironlake specific code.

Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -4652,16 +4652,8 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 		if (is_lvds && has_reduced_clock && i915_powersave) {
 			I915_WRITE(intel_crtc->pch_pll->fp1_reg, fp2);
 			intel_crtc->lowfreq_avail = true;
-			if (HAS_PIPE_CXSR(dev)) {
-				DRM_DEBUG_KMS("enabling CxSR downclocking\n");
-				pipeconf |= PIPECONF_CXSR_DOWNCLOCK;
-			}
 		} else {
 			I915_WRITE(intel_crtc->pch_pll->fp1_reg, fp);
-			if (HAS_PIPE_CXSR(dev)) {
-				DRM_DEBUG_KMS("disabling CxSR downclocking\n");
-				pipeconf &= ~PIPECONF_CXSR_DOWNCLOCK;
-			}
 		}
 	}