net: ethernet: davinci_emac: Deduplicate bus_find_device() by name matching

No need to reinvent the wheel, we have bus_find_device_by_name().

Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: David S. Miller <davem@davemloft.net>