MAINTAINERS: make IOAT easier to find

Searching MAINTAINERS for "ioat" comes up empty.  Fix this.

Cc: "Dan Williams" <dan.j.williams@intel.com>
Cc: "Sosnowski, Maciej" <maciej.sosnowski@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>