Call acpi_video_register() in intel_opregion_init() failure path
If i915 opregion is present, the acpi_video driver doesn't register
itself immediately; it defers that until the i915 opregion code is done.
But if that *fails*, the acpi_video driver was never getting registered.
And thus I have no backlight support on my Lenovo IdeaPad S10-3.
Call acpi_video_register() on the failure path, and it works again.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org> Acked-by: Matthew Garrett <mjg@redhat.com>