mm: zswap: switch maintainers to recently active developers and reviewers

Yosry, Nhat and I have been doing most of the recent development and
reviewing of changes in this space.  

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Dan Streetman <ddstreet@ieee.org>
Acked-by: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>