drm/i915/huc: check HuC and GuC version compatibility on MTL

Due to a change in the auth flow on MTL, GuC 70.7.0 and newer will only
be able to authenticate HuC 8.5.1 and newer. The plan is to update the 2
binaries synchronously in linux-firmware so that the fw repo always has
a matching pair that works; still, it's better to check in the kernel so
we can print an error message and abort HuC loading if the binaries are
out of sync instead of failing the authentication.

v2: Add clarification comment, fix typo in commit msg, clean up variable
declaration (John)

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com> #v1
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230717234905.117114-1-daniele.ceraolospurio@intel.com