drm/i915: Remove the ICL specific TBT power domains

The spec calls the ICL TBT AUX power well instances TBT1-4 (similarly to
all later platforms), align the power domain names with the spec.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220414210657.1785773-16-imre.deak@intel.com