setup_per_zone_pages_min(): take zone->lock instead of zone->lru_lock

setup_per_zone_pages_min(): take zone->lock instead of zone->lru_lock

This replaces zone->lru_lock in setup_per_zone_pages_min() with zone->lock.
There seems to be no need for the lru_lock anymore, but there is a need for
zone->lock instead, because that function may call move_freepages() via
setup_zone_migrate_reserve().

Signed-off-by: Gerald Schaefer <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Tested-by: Yasunori Goto <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>