arm64: dts: rockchip: Fix typo in rk3368 sdmmc card detect pin name

The card detect pin is currently called sdmcc-cd.
This patch fixes the typo and renames the pin to sdmmc-cd.

Signed-off-by: Matthias Brugger <mbrugger@suse.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>