ARM: dts: berlin: add a required reset property in the chip controller node

The chip controller node now also describes the Marvell Berlin reset
controller. Add the required 'reset-cells' property.

Signed-off-by: Antoine Ténart <antoine.tenart@free-electrons.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>