net: ti: cpsw: convert to use dev/ofnode api

Conver TI CPSW driver to use dev/ofnode api.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
[trini: Add <dm/ofnode.h> to provide the prototype to ofnode]
Signed-off-by: Tom Rini <trini@konsulko.com>