drm/i915: cancel the hangcheck before runtime suspend

The hangcheck function requires the hardware to be working, and if
we're suspending we're going to put the HW in D3 state.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -917,6 +917,7 @@ static int i915_runtime_suspend(struct device *device)
 
 	DRM_DEBUG_KMS("Suspending device\n");
 
+	del_timer_sync(&dev_priv->gpu_error.hangcheck_timer);
 	dev_priv->pm.suspended = true;
 	intel_opregion_notify_adapter(dev, PCI_D3cold);