arm64: dts: rockchip: Fix i2s0 pin conflict on ROCK Pi 4 boards

Commit 91419ae0 ("arm64: dts: rockchip: use BCLK to GPIO switch on
rk3399") modified i2s0 to switch the corresponding pins off when idle.
For the ROCK Pi 4 boards, this means that i2s0 has the following pinctrl
setting:

    pinctrl-names = "bclk_on", "bclk_off";
    pinctrl-0 = <&i2s0_2ch_bus>;
    pinctrl-1 = <&i2s0_8ch_bus_bclk_off>;

Due to this change, i2s0 fails to probe on my Radxa ROCK 4SE and ROCK Pi
4B boards:

    rockchip-pinctrl pinctrl: pin gpio3-29 already requested by leds; cannot claim for ff880000.i2s
    rockchip-pinctrl pinctrl: pin-125 (ff880000.i2s) status -22
    rockchip-pinctrl pinctrl: could not request pin 125 (gpio3-29) from group i2s0-8ch-bus-bclk-off  on device rockchip-pinctrl
    rockchip-i2s ff880000.i2s: Error applying setting, reverse things back
    rockchip-i2s ff880000.i2s: bclk disable failed -22

A pin requested for i2s0_8ch_bus_bclk_off has already been requested by
user_led2, so whichever driver probes first will have the pin allocated.

The hardware uses 2-channel i2s so fix this error by setting pinctl-1 to
i2s0_2ch_bus_bclk_off which doesn't contain the pin allocated to user_led2.

I checked the schematics for all Radxa boards based on ROCK Pi 4 and this
change is compatible with all boards.

Fixes: 91419ae0 ("arm64: dts: rockchip: use BCLK to GPIO switch on rk3399")
Signed-off-by: Christopher Obbard <chris.obbard@collabora.com>
Series-to: linux-rockchip@lists.infradead.org
Series-cc: kernel@collabora.com
Series-version: 1
Cover-letter:
Fix i2s0 pin conflict on ROCK Pi 4 RK3399 boards
i2s0 fails to probe on my Radxa ROCK 4SE and ROCK Pi 4B boards with:

    rockchip-pinctrl pinctrl: pin gpio3-29 already requested by leds; cannot claim for ff880000.i2s
    rockchip-pinctrl pinctrl: pin-125 (ff880000.i2s) status -22
    rockchip-pinctrl pinctrl: could not request pin 125 (gpio3-29) from group i2s0-8ch-bus-bclk-off  on device rockchip-pinctrl
    rockchip-i2s ff880000.i2s: Error applying setting, reverse things back
    rockchip-i2s ff880000.i2s: bclk disable failed -22

This is due to the pinctl attempting to request a GPIO which the boards
use for a different function.

The first patch adds a missing pinctl node i2s0_2ch_bus_bclk_off to the
RK3399 devicetree.

The second patch sets the i2s0 pinctrl to use the new node when idle and
fixes the issue.
END