phy: ti: gmii-sel: simplify config dependencies between net drivers and gmii phy

The phy-gmii-sel can be only auto selected in Kconfig and now the pretty
complex Kconfig dependencies are defined for phy-gmii-sel driver, which
also need to be updated every time phy-gmii-sel is re-used for any new
networking driver.

Simplify Kconfig definition for phy-gmii-sel PHY driver - drop all
dependencies and from networking drivers and rely on using 'imply
PHY_TI_GMII_SEL' in Kconfig definitions for networking drivers instead.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
Tested-by: Murali Karicheri <m-karicheri2@ti.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>