drm/i915: Don't disable PPGTT for CHV based in PCI rev

In
 commit 62942ed7279d3e06dc15ae3d47665eff3b373327
 Author: Jesse Barnes <jbarnes@virtuousgeek.org>
 Date:   Fri Jun 13 09:28:33 2014 -0700

    drm/i915/vlv: disable PPGTT on early revs v3

we forgot about CHV. IS_VALLEYVIEW() is true for CHV, so we need to
explicitly avoid disabling PPGTT on CHV.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Deepak S <deepak.s@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -64,7 +64,8 @@ static int sanitize_enable_ppgtt(struct drm_device *dev, int enable_ppgtt)
 #endif
 
 	/* Early VLV doesn't have this */
-	if (IS_VALLEYVIEW(dev) && dev->pdev->revision < 0xb) {
+	if (IS_VALLEYVIEW(dev) && !IS_CHERRYVIEW(dev) &&
+	    dev->pdev->revision < 0xb) {
 		DRM_DEBUG_DRIVER("disabling PPGTT on pre-B3 step VLV\n");
 		return 0;
 	}