arm64: dts: rockchip: aliase sdmmc as mmc1 for Cool Pi 4B

Follow others rk3588 based boards, and u-boot only use mmc0/1
as mmc boot targets, so aliase sdmmc as mmc1.

Fixes: 3f5d336d

 ("arm64: dts: rockchip: Add support for rk3588s based board Cool Pi 4B")
Signed-off-by: Andy Yan <andyshrk@163.com>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Link: https://lore.kernel.org/r/20240201121106.1471301-1-andyshrk@163.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>