The phy-mode property must be defined on the MAC instead of the PHY. Define
phy-mode under gmac1 which the external phy is connected to.
Tested-by: Petr Louda <petr.louda@outlook.cz>
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
(cherry picked from commit 5155200f97adaeaaac7b752b5a6a5e41cba3db6a)
3fd3d99e3a