arm64: zynqmp: Enable nand driver for dc2 and dc3

Add description for nand devices on zc1751 dc2 and dc3 boards.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/e103821bdb717132559e780f1a4f4f6fefc95688.1623684253.git.michal.simek@xilinx.com