drm/i915: Enable GPU reset on Ivybridge.

According to the hardware documentation, GDRST is exactly the same as on
Sandybridge.  So simply enable the existing code.
Signed-off-by: NKenneth Graunke <kenneth@whitecape.org>
Signed-off-by: NKeith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/i915_drv.c

@@ -577,6 +577,7 @@ int i915_reset(struct drm_device *dev, u8 flags)
 	if (get_seconds() - dev_priv->last_gpu_reset < 5) {
 		DRM_ERROR("GPU hanging too fast, declaring wedged!\n");
 	} else switch (INTEL_INFO(dev)->gen) {
+	case 7:
 	case 6:
 		ret = gen6_do_reset(dev, flags);
 		/* If reset with a user forcewake, try to restore */