drm/i915: Move updating color management to before vblank evasion

This cannot be done reliably during vblank evasasion
since the color management registers are not double buffered.

The original commit that moved it always during vblank evasion was
wrong, so revert it to before vblank evasion again.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: 20a34e78

 ("drm/i915: Update color management during vblank evasion.")
Cc: stable@vger.kernel.org # v4.7+
Link: http://patchwork.freedesktop.org/patch/msgid/1488292128-14540-1-git-send-email-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>