sxgbe: fix driver probe error path and driver removal leaks

sxgbe_drv_probe:  mdio and priv->hw leaks
sxgbe_drv_remove: clk and priv->hw leaks

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Acked-by: Byungho An <bh74.an@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>