ARM: mvebu: enable Armada 39x in mvebu_v7_defconfig

Following the introduction of the Marvell Armada 39x support, let's
enabled it by default in mvebu_v7_defconfig.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm/configs/mvebu_v7_defconfig

@@ -12,6 +12,7 @@ CONFIG_ARCH_MVEBU=y
 CONFIG_MACH_ARMADA_370=y
 CONFIG_MACH_ARMADA_375=y
 CONFIG_MACH_ARMADA_38X=y
+CONFIG_MACH_ARMADA_39X=y
 CONFIG_MACH_ARMADA_XP=y
 CONFIG_MACH_DOVE=y
 CONFIG_PCI=y