drm/dp/i915: Make clock recovery in the link training compliant with DP Spec 1.2

drm/dp/i915: Make clock recovery in the link training compliant with DP Spec 1.2

This function cleans up clock recovery loop in link training compliant
tp Dp Spec 1.2. It tries the clock recovery 5 times for the same voltage
or until max voltage swing is reached and removes the additional non
compliant retries. This function now returns a boolean values based on
if clock recovery passed or failed.

v3:
* Better Debug prints in case of failures (Mika Kahola)
v2:
* Rebased on top of new revision of vswing patch (Manasi Navare)

Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>