MAINTAINERS: mark TI DaVinci list as "moderated"

TI DaVinci list is moderated for non-subscribers instead of
being "subscribers-only". Fix the way it appears in MAINTAINERS.

Without this the DaVinci list does not show up by default when using
scripts/get_maintainer.pl

Signed-off-by: Sekhar Nori <nsekhar@ti.com>