arm64: dts: marvell: espressobin: add ethernet alias

commit 5253cb8c00a6f4356760efb38bca0e0393aa06de upstream.

The maker of this board and its variants, stores MAC address in U-Boot
environment. Add alias for bootloader to recognise, to which ethernet
node inject the factory MAC address.

Signed-off-by: Tomasz Maciej Nowak <tmn505@gmail.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
[pali: Backported to 5.4 and older versions]
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>