fsl_pq_mdio: Fix fsl_pq_mdio to work with modules

This patch fixes the case when ucc_geth or gianfar are compiled
as modules. Without this patch the call to phy_connect() fails.

Signed-off-by: Ionut Nicu <ionut.nicu@freescale.com>
Acked-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>