ARM: dts: rockchip: convert rk3288 to operating-points-v2

Operating points need to be present in each cpu core using it, not only
the first one. With operating-points-v1 this would require duplicating
this table into each cpu node.

With opp-v2 we can share the same table on all nodes.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>