uboot-phytec

MAINTAINERS: Add myself as RCar/RMobile comaintainer

To help out with the RCar/RMobile upstreaming, I'm adding myself
as the RCar/RMobile maintainer.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>