drm/i915: vlv: fix switcheroo/legacy suspend/resume

During switcheroo/legacy suspend we don't call the suspend_late handler
but when resuming afterwards we call resume_early. This happened to work
so far, since suspend_late only disabled the PCI device. This changed in

commit 016970beb05da6285c2f3ed2bee1c676cb75972e
Author: Sagar Kamble <sagar.a.kamble@intel.com>
Date:   Wed Aug 13 23:07:06 2014 +0530

    drm/i915: Sharing platform specific sequence between runtime and system susp

after which we also saved/restored the VLV Gunit HW state in
suspend_late/resume_early. So now since we don't save the state during
suspend a following resume will restore a corrupted state.

Fix this by calling the suspend_late handler during both switcheroo and
legacy suspend.

CC: Sagar Kamble <sagar.a.kamble@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Sagar Kamble <sagar.a.kamble@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -670,11 +670,7 @@ int i915_suspend(struct drm_device *dev, pm_message_t state)
 	if (error)
 		return error;
 
-	/* Shut down the device */
-	pci_disable_device(dev->pdev);
-	pci_set_power_state(dev->pdev, PCI_D3hot);
-
-	return 0;
+	return i915_drm_suspend_late(dev);
 }
 
 static int i915_drm_thaw_early(struct drm_device *dev)
@@ -790,7 +786,7 @@ static int i915_resume_early(struct drm_device *dev)
 	return i915_drm_thaw_early(dev);
 }
 
-int i915_resume(struct drm_device *dev)
+static int i915_drm_resume(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
@@ -816,7 +812,12 @@ static int i915_resume_legacy(struct drm_device *dev)
 	if (ret)
 		return ret;
 
-	return i915_resume(dev);
+	return i915_drm_resume(dev);
+}
+
+int i915_resume(struct drm_device *dev)
+{
+	return i915_resume_legacy(dev);
 }
 
 /**
@@ -1004,7 +1005,7 @@ static int i915_pm_resume(struct device *dev)
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct drm_device *drm_dev = pci_get_drvdata(pdev);
 
-	return i915_resume(drm_dev);
+	return i915_drm_resume(drm_dev);
 }
 
 static int i915_pm_freeze(struct device *dev)