arm64: mvebu: armada-7040-db: Enable 10GB port 0 / SFI (KR)

This patch enables the mvpp2 port 0 usage on the Armada 7k DB by setting
the correct PHY type (KR / SFI) for the COMPHY driver and enabling the
ethernet0 device node in the dts.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Stefan Chulski <stefanc@marvell.com>
Cc: Kostya Porotchkin <kostap@marvell.com>
Cc: Nadav Haklai <nadavh@marvell.com>