This reverts

commit 1c80c25fb622973dd135878e98d172be20859049
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed May 18 18:47:12 2016 +0200

    drm/i915/psr: Make idle_frames sensible again

There are panels that needs 4 idle frames before entering PSR,
but VBT is unproperly set.

Also lately it was identified that idle frame count calculated at HW
can be off by 1, what makes the minimum of 2, at least.

Without the current vbt+1 we are with the risk of having HW calculating
0 idle frames and entering PSR when it shouldn't. Regardless the lack
of link training.

[Jani: there is some disagreement on the explanation, but the commit
regresses so revert it is.]

References: http://marc.info/?i=20160904191153.GA2328@light.dominikbrodowski.net
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Fixes: 1c80c25fb622 ("drm/i915/psr: Make idle_frames sensible again")
Cc: drm-intel-fixes@lists.freedesktop.org # v4.8-rc1+
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1473295351-8766-1-git-send-email-rodrigo.vivi@intel.com
(cherry picked from commit 40918e0bb81be02f507a941f8b2741f0dc1771b0)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>