drm/atomic: Fix outdated comment.

Commit 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
adds reference counting to atomic state, but didn't update the comments
in drm_atomic_(nonblocking_)commit. Clarify lifetime a bit more.

Fixes: 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.10-rc1+
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/7acd1c78-ea86-7776-d98d-c846186e4b88@linux.intel.com

drivers/gpu/drm/drm_atomic.c

@@ -1599,10 +1599,8 @@ EXPORT_SYMBOL(drm_atomic_check_only);
  * more locks but encountered a deadlock. The caller must then do the usual w/w
  * backoff dance and restart. All other errors are fatal.
  *
- * Also note that on successful execution ownership of @state is transferred
- * from the caller of this function to the function itself. The caller must not
- * free or in any other way access @state. If the function fails then the caller
- * must clean up @state itself.
+ * This function will take its own reference on @state.
+ * Callers should always release their reference with drm_atomic_state_put().
  *
  * Returns:
  * 0 on success, negative error code on failure.
@@ -1630,10 +1628,8 @@ EXPORT_SYMBOL(drm_atomic_commit);
  * more locks but encountered a deadlock. The caller must then do the usual w/w
  * backoff dance and restart. All other errors are fatal.
  *
- * Also note that on successful execution ownership of @state is transferred
- * from the caller of this function to the function itself. The caller must not
- * free or in any other way access @state. If the function fails then the caller
- * must clean up @state itself.
+ * This function will take its own reference on @state.
+ * Callers should always release their reference with drm_atomic_state_put().
  *
  * Returns:
  * 0 on success, negative error code on failure.