drm/xe/display: Spin-off xe_display runtime/d3cold sequences

No functional change. This patch only splits the xe_display_pm
suspend/resume functions in the regular suspend/resume from the
runtime/d3cold ones.

v2: - Rename d3cold functions (Jonathan)
    - Rebase

Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250218010330.761340-1-rodrigo.vivi@intel.com


Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>