arm64: dts: rockchip: add default pinctrl for rk3588 emmc

Add a default pinctrl definition for the rk3588 emmc.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20230531161220.280744-2-macroalpha82@gmail.com


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