drm/i915/dg2: Enable 5th port

DG2 supports a 5th display output which the hardware refers to as "TC1,"
even though it isn't a Type-C output.  This behaves similarly to the TC1
on past platforms with just a couple minor differences:

 * DG2's TC1 bit in SDEISR is at bit 25 rather than 24 as it is on
   ICP/TGP/ADP.
 * DG2 doesn't need the hpd inversion setting that we had to use on DG1

v2:
  intel_ddi_init(dev_priv, PORT_TC1); [Matt]

Cc: Swathi Dhanavanthri <swathi.dhanavanthri@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220218010328.183423-3-lucas.demarchi@intel.com