MAINTAINERS: update entry for Marvell ARM platform maintainers

The Marvell platform support is no longer limited to Armada 370, 375,
38x and XP, but now also includes the 32-bits Armada 39x and the
64-bits Armada 3700 and 7K/8K.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

MAINTAINERS

@@ -1310,7 +1310,7 @@ ARM/MAGICIAN MACHINE SUPPORT
 M:	Philipp Zabel <philipp.zabel@gmail.com>
 S:	Maintained
 
-ARM/Marvell Kirkwood and Armada 370, 375, 38x, XP SOC support
+ARM/Marvell Kirkwood and Armada 370, 375, 38x, 39x, XP, 3700, 7K/8K SOC support
 M:	Jason Cooper <jason@lakedaemon.net>
 M:	Andrew Lunn <andrew@lunn.ch>
 M:	Gregory Clement <gregory.clement@free-electrons.com>