drm/i915: Move the power domain->well mappings to intel_display_power_map.c

Move the list of platform specific power domain -> power well
definitions to intel_display_power_map.c. While at it group the
platforms' power domain macros with the corresponding power well lists
and keep all the power domain lists in the same order (matching the enum
order).

No functional changes.

v2:
- s/intel_display_power_internal.h/intel_display_power_map.h/ (Jani)
- Simplify intel_cleanup_power_wells().
- Don't move intel_display_power_domain_str().
v3:
- Rename intel_init/cleanup_power_wells() to
  intel_display_power_map_init/cleanup().
- Add documentation to intel_display_power_map_init/cleanup().

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220414210657.1785773-3-imre.deak@intel.com