drm/atomic: doc: remove old comment about nonblocking commits

We now support nonblocking commits on drm_atomic_helper_commit()
so the comment is not valid anymore.

Signed-off-by: Gustavo Padovan <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/drm_atomic_helper.c

···
  * function implements nonblocking commits, using
  * drm_atomic_helper_setup_commit() and related functions.
  *
- * Note that right now this function does not support nonblocking commits, hence
- * driver writers must implement their own version for now.
- *
  * Committing the actual hardware state is done through the
  * ->atomic_commit_tail() callback of the &drm_mode_config_helper_funcs vtable,
  * or it's default implementation drm_atomic_helper_commit_tail().