ARM: dts: k2g-evm: remove unused phy-mode property from phy node

ARM: dts: k2g-evm: remove unused phy-mode property from phy node

This patch removes the unused phy-mode property from the phy dt node. On
K2G, currently link-interface determines if phy is used or not and is
already set to use rgmii. So this is not needed. Besides phy-mode should
be added to slave interface configuration of the cpsw driver, not in the
phy node.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>