arm64: dts: fsl: layerscape: fix warnings when compiling dts files

arm64: dts: fsl: layerscape: fix warnings when compiling dts files

when compiling dts file using DTC_FLAG='-@', the device tree compiler
reports these warnings:

Warning (simple_bus_reg): /soc/mdio@0x8c0b000: simple-bus unit address
format error, expected "8c0b000"
Warning (unit_address_format): /pfe@04000000: unit name should not have
leading 0s

Fixed the node names to silence these warnings.

Signed-off-by: Pankaj Bansal <pankaj.bansal@nxp.com>