ARM: dts: kirkwood: lsxl: remove first ethernet port

Both the Linkstation LS-CHLv2 and the LS-XHL have only one ethernet
port. This has always been wrong, i.e. the board code used to set up
both ports, but the driver will play nice and return -ENODEV if the
assiciated PHY is not found. Nevertheless, it is wrong. Remove it.

Fixes: 876e2333 ("ARM: kirkwood: add gigabit ethernet and mvmdio device tree nodes")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>