ARM: dts: rockchip: rename RK1108-evb to RV1108-evb

Rockchip finally named the SOC as RV1108, so change it
for compatible.

The rk1108/rv1108 is completely new to the market, so there no real
devices exist in the wild, only the Rockchip internal evaluation
board. Therefore we're not breaking any existing devices when
changing compatible values.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Acked-by: Rob Herring <robh@kernel.org>

[added paragraph about no real devices existing]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>