mm/list_lru.c: move locking from __list_lru_walk_one() to its caller

mm/list_lru.c: move locking from __list_lru_walk_one() to its caller

Move the locking inside __list_lru_walk_one() to its caller.  This is a
preparation step in order to introduce list_lru_walk_one_irq() which
does spin_lock_irq() instead of spin_lock() for the locking.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Reviewed-by: Vladimir Davydov <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>