mm: remove __GFP_NOFAIL is deprecated comment

Commit 64775719 ("mm: clarify __GFP_NOFAIL deprecation status") was
incomplete and didn't remove the comment about __GFP_NOFAIL being
deprecated in buffered_rmqueue.

Let's get rid of this leftover but keep the WARN_ON_ONCE for order > 1
because we should really discourage from using __GFP_NOFAIL with higher
order allocations because those are just too subtle.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>