net: phy: mdio-bcm-unimac: NULL-terminate unimac_mdio_ids

drivers/net/phy/mdio-bcm-unimac.c:195:37-38: unimac_mdio_ids is not NULL
terminated at line 195

Make sure of_device_id tables are NULL terminated
Generated by: scripts/coccinelle/misc/of_table.cocci

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>