Vswing sequences on BXT and CNL are equivalent
to the ddi buffer registers setting on other platforms.

For some reason it got aligned with skl_ddi_set_iboost what
is semantically incorrect. This forced us to keep skipping
ddi buffer translation tables on the platforms that has
the vswing sequences.

v2: Don't mess with DP signal levels on this patch.

Cc: Vandana Kannan <vandana.kannan@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170829232230.23051-3-rodrigo.vivi@intel.com