ARM: dts: BCM953012HR: Add ethernet aliases

Adding ethernet aliases.  These are used, for example, by bootloaders,
to modify the MAC addresses in the device tree.

Signed-off-by: Steve Lin <steven.lin1@broadcom.com>
Acked-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>