encoder->type is unreliable for DP/HDMI, so pass it in explicity into
cnl_ddi_vswing_sequence(). This matches what we do for BXT.

v2: Pass intel_encoder down to cnl_ddi_vswing_program(), and
    clean up the argument types while at it
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171016145705.11780-7-ville.syrjala@linux.intel.comReviewed-by: James Ausmus <james.ausmus@intel.com>