drm/i915/huc: Remove unused intel_huc_fini()

This function is no longer used. Its functionality is covered
by intel_uc_fini_fw().

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>