drm/i915/display: Fix the encoder type check

For all ddi, encoder->type holds output type as ddi,
assigning it to individual o/p types is no more valid.

Fixes: 362bfb99 ("drm/i915/tgl: Add DKL PHY vswing table for HDMI")

v2: Rebase, no functional change.

Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200612082237.11886-1-vandita.kulkarni@intel.com