ARM: zynq: Add nand controller node in zynq-ces-nand dt

Add memory-controller@e000e000 node in zynq-ces-nand.dts as
zynq_nand driver utilizes flash@e1000000 node. Without this
dt node mini nand u-boot does not probe.

Signed-off-by: T Karthik Reddy <t.karthik.reddy@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>