MAINTAINERS: remove Lorenzo as vmalloc reviewer

MAINTAINERS: remove Lorenzo as vmalloc reviewer

I haven't had the bandwidth to review vmalloc patches recently and I
suspect I won't be able to do so consistently moving forwards, so I think
it's best if I remove myself as reviewer for the time being.

Link: https://lkml.kernel.org/r/20240602205510.108807-1-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>