arm64: dts: rockchip: fix cpu compatible property for rk3308

A test with the command below gives for example these errors:

arch/arm64/boot/dts/rockchip/rk3308-evb.dt.yaml: cpu@0: compatible:
Additional items are not allowed ('arm,armv8' was unexpected)
arch/arm64/boot/dts/rockchip/rk3308-evb.dt.yaml: cpu@0: compatible:
['arm,cortex-a35', 'arm,armv8']
is too long

Fix these errors by removing the last argument of
the cpu compatible property in rk3308.dtsi.

make ARCH=arm64
dtbs_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/arm/cpus.yaml

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20200228084827.16198-1-jbx6244@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>