drm/i915: vlv: fix gunit HW state corruption during S4 suspend

drm/i915: vlv: fix gunit HW state corruption during S4 suspend

During S4 freeze we don't call intel_suspend_complete(), which would
save the gunit HW state, but during S4 thaw/restore events we call
intel_resume_prepare() which restores it, thus ending up in a corrupted
HW state.

Fix this by calling intel_suspend_complete() from the corresponding
freeze_late event handler.

The issue was introduced in
commit 016970beb05da6285c2f3ed2bee1c676cb75972e
Author: Sagar Kamble <[email protected]>
Date:   Wed Aug 13 23:07:06 2014 +0530

CC: Sagar Kamble <[email protected]>
Signed-off-by: Imre Deak <[email protected]>
Reviewed-by: Ville Syrjälä <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Signed-off-by: Jani Nikula <[email protected]>