MAINTAINERS: update SLAB ALLOCATOR maintainers

With permission, reduce the number of maintainers.  Create a CREDITS entry
for Joonsoo (Pekka already has one).  Thanks for all the work!

Link: https://lkml.kernel.org/r/20250410090021.72296-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Christoph Lameter (Ampere) <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: tehcaster

CREDITS

@@ -2071,6 +2071,10 @@ S: 660 Harvard Ave. #7
 S: Santa Clara, CA 95051
 S: USA
 
+N: Joonsoo Kim
+E: iamjoonsoo.kim@lge.com
+D: Slab allocators
+
 N: Kukjin Kim
 E: kgene@kernel.org
 D: Samsung S3C, S5P and Exynos ARM architectures

MAINTAINERS

@@ -22249,9 +22249,7 @@ F:	drivers/nvmem/layouts/sl28vpd.c
 
 SLAB ALLOCATOR
 M:	Christoph Lameter <cl@linux.com>
-M:	Pekka Enberg <penberg@kernel.org>
 M:	David Rientjes <rientjes@google.com>
-M:	Joonsoo Kim <iamjoonsoo.kim@lge.com>
 M:	Andrew Morton <akpm@linux-foundation.org>
 M:	Vlastimil Babka <vbabka@suse.cz>
 R:	Roman Gushchin <roman.gushchin@linux.dev>