Fix MCHBAR cleanup on the driver init error path

MCHBAR is cleaned up in i915_mmio_cleanup(), so the separate call in
i915_driver_load() is incorrect.

CC: David Weinehall <david.weinehall@intel.com>
Fixes: ad5c3d3ffbb2 ("drm/i915: Move MCHBAR setup earlier during init")
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458128348-15730-2-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/i915_dma.c

@@ -1175,7 +1175,6 @@ out_gem_unload:
 	if (dev->pdev->msi_enabled)
 		pci_disable_msi(dev->pdev);
 
-	intel_teardown_mchbar(dev);
 	pm_qos_remove_request(&dev_priv->pm_qos);
 	arch_phys_wc_del(dev_priv->gtt.mtrr);
 	io_mapping_free(dev_priv->gtt.mappable);