mm/vmscan.c: move check for SHRINKER_NUMA_AWARE to do_shrink_slab()

mm/vmscan.c: move check for SHRINKER_NUMA_AWARE to do_shrink_slab()

In case of shrink_slab_memcg() we do not zero nid, when shrinker is not
numa-aware.  This is not a real problem, since currently all memcg-aware
shrinkers are numa-aware too (we have two: super_block shrinker and
workingset shrinker), but something may change in the future.

Link: http://lkml.kernel.org/r/153320759911.18959.8842396230157677671.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Josef Bacik <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>