drm/i915/dp: Remove useless debug about TPS3 support

We already print training pattern used during link training and also
print if the source or sink does not support TPS3 for HBR2 link rates,
see intel_dp_training_pattern().

Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170918222141.4674-5-dhinakaran.pandiyan@intel.com