MAINTAINERS: add co-maintainer and reviewer for SLAB ALLOCATOR

Promote Harry Yoo from reviewer to maintainer.  Harry's been involved in
slab development for multiple years now and doing a great job.

Add Hao Li as a new reviewer.  Hao has been doing very useful reviews for
a while now, so make it official and ensure the Cc's.

Link: https://lkml.kernel.org/r/20260302101345.36713-2-vbabka@kernel.org
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Hao Li <hao.li@linux.dev>
Acked-by: SeongJae Park <sj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Vlastimil Babka (SUSE)

MAINTAINERS

@@ -24361,11 +24361,12 @@ F:	drivers/nvmem/layouts/sl28vpd.c
 
 SLAB ALLOCATOR
 M:	Vlastimil Babka <vbabka@kernel.org>
+M:	Harry Yoo <harry.yoo@oracle.com>
 M:	Andrew Morton <akpm@linux-foundation.org>
+R:	Hao Li <hao.li@linux.dev>
 R:	Christoph Lameter <cl@gentwo.org>
 R:	David Rientjes <rientjes@google.com>
 R:	Roman Gushchin <roman.gushchin@linux.dev>
-R:	Harry Yoo <harry.yoo@oracle.com>
 L:	linux-mm@kvack.org
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git