arm64: dts: freescale: ls1028a: Add standard PCI device compatible strings to ENETC

PCI devices should have a compatible string based on the vendor and device
IDs. Add these to the Freescale ENETC devices.

Putting the PCI compatible string first as vendor and device ID is more
specific than a compatible without any device specific information.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>