memcg-v1: fully deprecate move_charge_at_immigrate

Patch series "memcg-v1: fully deprecate charge moving".

The memcg v1's charge moving feature has been deprecated for almost 2
years and the kernel warns if someone try to use it.  This warning has
been backported to all stable kernel and there have not been any report of
the warning or the request to support this feature anymore.  Let's proceed
to fully deprecate this feature.


This patch (of 6):

Proceed with the complete deprecation of memcg v1's charge moving feature.
The deprecation warning has been in the kernel for almost two years and
has been ported to all stable kernel since.  Now is the time to fully
deprecate this feature.

Link: https://lkml.kernel.org/r/20241025012304.2473312-1-shakeel.butt@linux.dev
Link: https://lkml.kernel.org/r/20241025012304.2473312-2-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>