MAINTAINERS: transfer maintainership for the EZX platform

Neither Daniel, Harald or myself are looking into this anymore.
Robert thankfully agreed to handle the maintenance from now on.
Also remove the outdated entries for website, git tree and
mailing list.

Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Acked-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>