arm64: dts: add NAND board files for Stratix10 and Agilex

The Stratix10 and Agilex devkits support a separate NAND daughter card.
The NAND daughter card replaces the SDMMC slot that is on the default
daughter card thus requires a separate board dts file.

Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>