arm: kirkwood: Pogoplug V4 : Use Marvell network PHY driver

The Pogoplug V4 board has the network chip Marvell 88E1116R. So to
properly configure the network, enable CONFIG_PHY_MARVELL to activate
the compatible driver M88E1118R.

- This patch depends on the series:
https://patchwork.ozlabs.org/project/uboot/patch/20220124061712.28316-2-mibodhi@gmail.com/



Signed-off-by: Tony Dinh <mibodhi@gmail.com>