drm/i915/uc: Don't fail on HuC firmware failure

drm/i915/uc: Don't fail on HuC firmware failure

HuC is usually not a critical component, so we can safely ignore
firmware load or authentication failures unless HuC was explicitly
requested by the user.

v2: add convenient way to disable loading (Chris)

Signed-off-by: Michal Wajdeczko <[email protected]>
Cc: Daniele Ceraolo Spurio <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Reviewed-by: Chris Wilson <[email protected]> #v1
Signed-off-by: Chris Wilson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]