Assuming mac_clk is fed by an external clock, set clk_rmii_src
clock select control register from IO for rgmii interface.
Signed-off-by: David Wu <david.wu@rock-chips.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>