net: ethernet: ti: cpsw: deprecate cpsw-phy-sel driver

Deprecate cpsw-phy-sel driver as it's been replaced with new
TI phy-gmii-sel PHY driver.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>