drm/xe/huc: Prepare for 2-step HuC authentication

Starting on MTL, the HuC is authenticated twice, once via GuC (same as
with older integrated platforms) and once via GSC; the first
authentication allows the HuC to be used for clear-media workloads,
while the second one unlocks support for protected content.
Ahead of adding the authentication flow via GSC, this patch adds support
for differentiating the 2 auth steps and checking if they're complete.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Vivaik Balasubrawmanian <vivaik.balasubrawmanian@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>