ARM: dts: lpc32xx: ea3250: add unit address to memory device node

The change adds a unit address to memory device node, the issue was
reported as a unit_address_vs_reg warning by dtc.

Root device node properties #address-cells and #size-cells were
removed as inherited from lpc32xx.dtsi.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>