arm64: dts: rockchip: fix hdmi cec on rock-3a

arm64: dts: rockchip: fix hdmi cec on rock-3a

HDMI CEC is configured to select HDMITX_CEC_M0 function of GPIO0_C7 by
default in rk356x.dtsi. On Radxa ROCK 3 Model A it is routed to
HDMITX_CEC_M1 according to board schematic [1].

Fix HDMI CEC by overriding pinctrl in hdmi node to select HDMITX_CEC_M1.

[1] https://dl.radxa.com/rock3/docs/hw/3a/ROCK-3A-V1.3-SCH.pdf

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Link: https://lore.kernel.org/r/20230110225547.1563119-3-jonas@kwiboo.se
[added pinctrl-names duplicate]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>