arm64: dts: rockchip: vdd_log on rk3399-sapphire is not an i2c slave

The vdd_log power supply is controlled by a PWM pin, not by i2c
register access. There is a boot message that reports an error
about not being able to bring that supply up.

Signed-off-by: Vicente Bergas <vicencb@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>