drm/xe/pxp: Enable PXP for MTL and LNL

Now that are the pieces are there, we can turn the feature on.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129174140.948829-14-daniele.ceraolospurio@intel.com