drm/i915: Fix kerneldoc for intel_guc_fini

Recent refactoring forgot to update this one.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: bf9e8429 ("drm/i915: Make various init functions take dev_priv")
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1480668233-25372-1-git-send-email-tvrtko.ursulin@linux.intel.com