MAINTAINERS: Add dma-buf sharing framework maintainer

Adding maintainer info for dma-buf buffer sharing framework;
some mailing lists interested in this work are also added.

Signed-off-by: Sumit Semwal <sumit.semwal@ti.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Dave Airlie <airlied@redhat.com>