MAINTAINERS: ARM/Amlogic: add co-maintainer, misc. updates

Add myself as co-maintainer, update mailing list entry and add a couple
more directories.

Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Acked-by: Carlo Caione <carlo@caione.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>