ARM: mvebu: adjust Armada XP evaluation board DTS

The Armada XP evaluation board is based on the MV78460 Armava XP
SoC. Now that we have separate .dtsi files for the three different
SoCs of the Armada XP family, use the appropriate one as include for
the Armada XP evaluation board .dts file.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>