drm/i915/tgl: port to ddc pin mapping

drm/i915/tgl: port to ddc pin mapping

Make the icl function generic so it is based on phy type and can be
applied to tgl as well.

I checked if this could not apply to EHL as well, but unfortunately
there the HPD and DDC/GMBUS pins for DDI C are mapped to TypeC Port 1
even though it doesn't have TC phy.

v2: don't add a separate function for TGL, but rather reuse the ICL one
    (suggested by Rodrigo)
v3: rebase after the introduction of enum phy and use it for the
    conversions

Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190711173115.28296-19-lucas.demarchi@intel.com