mm/page_alloc: remove unnecessary parameter batch of nr_pcp_free

We get batch from pcp and just pass it to nr_pcp_free immediately.  Get
batch from pcp inside nr_pcp_free to remove unnecessary parameter batch.

Link: https://lkml.kernel.org/r/20230809100754.3094517-3-shikemeng@huaweicloud.com


Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>