drm/i915/rkl: Update TGP's pin mapping when paired with RKL

HPD pin handling for RKL+TGP is a special case; we effectively select
the HPD pin based on the DDI (A,B,D,E) rather than the PHY (A,B,C,D).
This differs from the regular behavior of RKL+CMP (and also TGL+TGP).

v2:
 - Rather than providing a custom hpd_pin mapping table, just assign
   encoder->hpd_pin in a custom manner for this setup.  (Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200606025740.3308880-4-matthew.d.roper@intel.com


Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>