drm/xe/pxp: Add VCS inline termination support

The key termination is done with a specific submission to the VCS
engine. This flow will be triggered in response to a termination
interrupt, whose handling is coming in a follow-up patch in the series.

v2: clean up defines and command emission code. (John)

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129174140.948829-4-daniele.ceraolospurio@intel.com