drm/i915: Split gen11_hpd_detection_setup() into tc vs. tbt variants

No reason to stuff both type-c and tbt into the same function.
Let's split this so we may more easily handle platforms that
lack the tbt spefific bits.

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201028213323.5423-14-ville.syrjala@linux.intel.com