When using ZMII for MDIO only (such as 440GX with RGMII for data and ZMII for
MDIO), the ZMII code would fail to properly refcount, thus triggering a
BUG_ON().
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>