mm/memcg: minor cleanup for MEM_CGROUP_ID_MAX

MEM_CGROUP_ID_MAX is only used when CONFIG_MEMCG is configured.  So remove
unneeded !CONFIG_MEMCG variant.  Also it's only used in
mem_cgroup_alloc(), so move it from memcontrol.h to memcontrol.c.  And
further define it as:

  #define MEM_CGROUP_ID_MAX ((1UL << MEM_CGROUP_ID_SHIFT) - 1)

so if someone changes MEM_CGROUP_ID_SHIFT in the future, then
MEM_CGROUP_ID_MAX will be updated accordingly, as suggested by Muchun.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Shakeel Butt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions