drm/xe: Add caching pagetable flag

drm/xe: Add caching pagetable flag

Introduce device xe_caching_pt flag to selectively turn it on for
supported platforms. It allows to eliminate version check and enable
this feature for the future platforms.

Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patch.msgid.link/20251125153732.400766-2-zbigniew.kempczynski@intel.com