arm: dts: armada-cp110-slave: add missing cps_nand

Align node properties to kernel dts node.

Keep U-Boot specific nand-enable-arbiter, and num-cs for compatibility
with the current driver.

Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Shmuel Hazan <shmuel.h@siklu.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>