ARM: dove: move device tree nodes to DT irqchip and clocksource

With recent support for true irqchip and clocksource drivers for Orion
SoCs, now make use of it on DT enabled Dove boards.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>