MAINTAINERS: Add myself as co-maintainer to the legacy support of the mvebu SoCs

I will also take care of the legacy support(not fully converted to DT)
of the mvebu SoCs.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NJason Cooper <jason@lakedaemon.net>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

MAINTAINERS

@@ -1198,6 +1198,7 @@ ARM/Marvell Dove/MV78xx0/Orion SOC support
 M:	Jason Cooper <jason@lakedaemon.net>
 M:	Andrew Lunn <andrew@lunn.ch>
 M:	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
+M:	Gregory Clement <gregory.clement@free-electrons.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 F:	arch/arm/mach-dove/