zsmalloc: add maintainers

tAdd adds maintainer information for zsmalloc into the MAINTAINERS file.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit eae70d06846199afc97524ed986b910836c0abe5)