vmscan: convert mm_vmscan_lru_isolate to DEFINE_EVENT

vmscan: convert mm_vmscan_lru_isolate to DEFINE_EVENT

Mel Gorman recently added some vmscan tracepoints.  Unfortunately they are
covered only global reclaim.  But we want to trace memcg reclaim too.

Thus, this patch convert them to DEFINE_TRACE macro.  it help to reuse
tracepoint definition for other similar usage (i.e.  memcg).  This patch
have no functionally change.

Signed-off-by: KOSAKI Motohiro <[email protected]>
Reviewed-by: KAMEZAWA Hiroyuki <[email protected]>
Acked-by: Balbir Singh <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>