Include memory node unit name in order to fix the following W=1
warnings:

Warning (unit_address_vs_reg): Node /memory has a reg or ranges property, but no unit name
Signed-off-by: NFabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>