ARM: dts: turris-omnia: Add ethernet aliases

This allows bootloader to correctly pass MAC addresses used by bootloader
to individual interfaces into kernel device tree.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 26ca8b52 ("ARM: dts: add support for Turris Omnia")
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>