net: stmmac: sun8i: remove of_get_phy_mode()

net: stmmac: sun8i: remove of_get_phy_mode()

devm_stmmac_probe_config_dt() already gets the PHY mode from firmware,
which is stored in plat_dat->phy_interface. Therefore, we don't need to
get it in platform code.

sun8i was using of_get_phy_mode() to set plat_dat->mac_interface, which
defaults to plat_dat->phy_interface when the mac-mode DT property is
not present. As nothing in arch/*/boot/dts sets the mac-mode property,
it is highly likely that these two will be identical, and thus there
is no need for this glue driver to set plat_dat->mac_interface.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1tsIGs-005v09-CD@rmk-PC.armlinux.org.uk
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>