arm64: dts: ls1088ardb: add QSGMII PHY nodes

Annotate the external MDIO1 node and describe the 8 QSGMII PHYs found on
the LS1088ARDB board and add phy-handles for DPMACs 3-10 to its
associated PHY.  Also, add the internal PCS MDIO nodes for the internal
MDIO buses found on the LS1088A SoC along with their internal PCS PHY
and link the corresponding DPMAC to the PCS through the pcs-handle.
Also, rename the dpmac@x nodes to ethernet@x in order to be compliant
with the naming convention used by ethernet controllers.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>