phy: ti: gmii-sel: fix set of copy-paste errors

- under PHY_INTERFACE_MODE_MII the 'mode' func parameter is assigned
instead of 'gmii_sel_mode' and it's working only because the default value
'gmii_sel_mode' is set to 0.

- console outputs use 'rgmii_id' and 'mode' values to print PHY mode
instead of using 'submode' value which is representing PHY interface mode
now.

This patch fixes above two cases.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>