arm64: dts: rockchip: remove #sound-dai-cells from &i2s1 node of rk3399-pinebook-pro.dts

The '#sound-dai-cells' property is already defined in rk3399.dtsi
at the 'i2s1' node, so remove it from the '&i2s1' node in
'rk3399-pinebook-pro.dts'.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20200424155600.24254-1-jbx6244@gmail.com


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