drm/xe: Drop useless d3cold allowed message

This message just spams dmesg providing little benefit. Remove it.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241115192155.2050987-1-matthew.brost@intel.com