drm/xe/pxp: Add GSC session invalidation support

After a session is terminated, we need to inform the GSC so that it can
clean up its side of the allocation. This is done by sending an
invalidation command with the session ID.
The invalidation will be triggered in response to a termination,
interrupt, whose handling is coming in the next patch in the series.

v2: Better comment and error messages (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/20250129174140.948829-5-daniele.ceraolospurio@intel.com