The fence is only tracking if the HuC load is in progress or not and
doesn't distinguish between already loaded, not supported or disabled,
so we can always initialize it to completed, no matter the actual
support. We already do that for most platforms, but we skip it on
GTs that lack VCS engines (e.g. MTL root GT), so fix that. Note that the
cleanup is already unconditional.

While at it, move the init/fini to helper functions.

Fixes: 8e5f3782 ("drm/i915/huc: fix leak of debug object in huc load fence on driver unload")
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221123235417.1475709-1-daniele.ceraolospurio@intel.com
(cherry picked from commit 14347a9c)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>