add alias for sdmmc as mmc1.
make card detect work.

Fixes: ea3e66e7 ("arm64: dts: rockchip: add SD card support to rock-5a")
Fixes: 2a6d4af5 ("arm64: dts: rockchip: Add SD card support to rock-5b")
Signed-off-by: FUKAUMI Naoki <naoki@radxa.com>
Link: https://lore.kernel.org/r/20230722121150.130126-1-naoki@radxa.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>