drm/i915: Rename the power domain names to end with pipes/ports

Make all power domain names end with the pipe/port instance for
consistency.

No functional changes.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220414210657.1785773-6-imre.deak@intel.com