MAINTAINERS: add myself as vmalloc co-maintainer

MAINTAINERS: add myself as vmalloc co-maintainer

I have been working on the vmalloc code for several years, contributing to
improvements and fixes.  Add myself as co-maintainer ("M") alongside
Andrew Morton.

Link: https://lkml.kernel.org/r/20250507150257.61485-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>