vmscan: kill sc.swap_cluster_max

vmscan: kill sc.swap_cluster_max

Now, All caller of reclaim use swap_cluster_max as SWAP_CLUSTER_MAX.
Then, we can remove it perfectly.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>