Neither the DP spec nor the compliance test spec state or imply that we
should write the DP_TRAINING_PATTERN_SET at every voltage swing and
pre-emphasis change. Indeed we probably shouldn't. So don't.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49402Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Smoke-tested-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>