drm/i915: Move VLV cmnlane workaround to intel_power_domains_init_hw()

Now that the CMNRESET deassert is part of the cmnlane power well,
intel_reset_dpio() is called too late to make any difference. We've
deasserted CMNRESET by that time, and so the off+on toggle w/a will
never kick in.

Move the workaround to intel_power_domains_init_hw() where it gets
called before we enable the init power domain.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>