mm/vmscan: remove redundant __GFP_NOWARN

mm/vmscan: remove redundant __GFP_NOWARN

The __GFP_NOWARN flag was included in GFP_NOWAIT since commit 16f5dfbc851b
("gfp: include __GFP_NOWARN in GFP_NOWAIT").  So remove the redundant
__GFP_NOWARN flag.

Link: https://lkml.kernel.org/r/20251006014948.44695-1-wangfushuai@baidu.com
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>