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: NMarek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>

MAINTAINERS

@@ -133,6 +133,7 @@ F:	arch/arm/include/asm/arch-pxa/
 
 ARM RENESAS RMOBILE/R-CAR
 M:	Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
+M:	Marek Vasut <marek.vasut+renesas@gmail.com>
 S:	Maintained
 T:	git git://git.denx.de/u-boot-sh.git
 F:	arch/arm/mach-rmobile/